High severityNVD Advisory· Published Jul 15, 2019· Updated Aug 4, 2024

CVE-2019-1062

Description

A remote code execution vulnerability in Chakra scripting engine due to memory corruption, exploitable in Microsoft Edge.

AI Insight

LLM-synthesized narrative grounded in this CVE's description and references.

A remote code execution vulnerability in Chakra scripting engine due to memory corruption, exploitable in Microsoft Edge.

CVE-2019-1062 is a remote code execution vulnerability in the Chakra scripting engine, used by Microsoft Edge. The issue stems from how Chakra handles objects in memory, specifically a type confusion in the JIT compiler's property access optimization [3]. A memory corruption can occur when the engine incorrectly determines object layout changes, leading to potential exploitation [1].

To exploit this vulnerability, an attacker would need to host a specially crafted website and convince a user to visit it via social engineering or drive-by download. The vulnerability is triggered when the user's browser processes the malicious JavaScript, causing memory corruption in the Chakra engine [2]. No additional privileges or user interaction beyond visiting the site are required.

Successful exploitation could allow the attacker to execute arbitrary code in the context of the current user. If the user has administrative rights, the attacker could gain full control of the system, including installing programs, viewing/editing data, or creating new accounts [2].

Microsoft addressed this vulnerability in the July 2019 security update for Microsoft Edge and in the ChakraCore open-source project via commits [1][3]. Users are advised to apply the latest updates to mitigate the risk.

References

AI Insight generated on May 22, 2026. Synthesized from this CVE's description and the cited reference URLs; citations are validated against the source bundle.

Affected packages

Versions sourced from the GitHub Security Advisory.

Package	Affected versions	Patched versions
Microsoft.ChakraCoreNuGet	< 1.11.11	1.11.11

Affected products

ghsa-coords
pkg:nuget/microsoft.chakracore
Range: < 1.11.11
Microsoft/Chakracorecpe-rescue
Range: unspecified
Microsoft/Edgecpe-rescue
Range: Windows 10 for 32-bit Systems
Microsoft/Microsoft Edge on Windows 10 Version 1903 for 32-bit Systemsv5
Range: unspecified
Microsoft/Microsoft Edge on Windows 10 Version 1903 for ARM64-based Systemsv5
Range: unspecified
Microsoft/Microsoft Edge on Windows 10 Version 1903 for x64-based Systemsv5
Range: unspecified

Patches

75162b7f2d8a

[MERGE #6196 @atulkatti] ChakraCore servicing update for July, 2019

https://github.com/chakra-core/ChakraCoreAtul KattiJul 9, 2019via ghsa

commit

16 files changed · +81 −27

Build/NuGet/.pack-version+1 −1 modified
```
@@ -1 +1 @@
-1.11.10
+1.11.11
```

lib/Backend/BackwardPass.cpp+8 −4 modified

@@ -4151,13 +4151,17 @@ BackwardPass::UpdateImplicitCallBailOutKind(IR::Instr *const instr, bool needsBa
 
     IR::BailOutKind implicitCallBailOutKind = needsBailOutOnImplicitCall ? IR::BailOutOnImplicitCalls : IR::BailOutInvalid;
 
-    const IR::BailOutKind instrBailOutKind = instr->GetBailOutKind();
+    IR::BailOutKind instrBailOutKind = instr->GetBailOutKind();
     if (instrBailOutKind & IR::BailOutMarkTempObject)
     {
-        // Don't remove the implicit call pre op bailout for mark temp object
         // Remove the mark temp object bit, as we don't need it after the dead store pass
-        instr->SetBailOutKind(instrBailOutKind & ~IR::BailOutMarkTempObject);
-        return true;
+        instrBailOutKind &= ~IR::BailOutMarkTempObject;
+        instr->SetBailOutKind(instrBailOutKind);
+
+        if (!instr->GetBailOutInfo()->canDeadStore)
+        {
+            return true;
+        }
     }
 
     const IR::BailOutKind instrImplicitCallBailOutKind = instrBailOutKind & ~IR::BailOutKindBits;

lib/Backend/BailOut.h+2 −1 modified

@@ -27,7 +27,7 @@ class BailOutInfo
     BailOutInfo(uint32 bailOutOffset, Func* bailOutFunc) :
         bailOutOffset(bailOutOffset), bailOutFunc(bailOutFunc),
         byteCodeUpwardExposedUsed(nullptr), polymorphicCacheIndex((uint)-1), startCallCount(0), startCallInfo(nullptr), bailOutInstr(nullptr),
-        totalOutParamCount(0), argOutSyms(nullptr), bailOutRecord(nullptr), wasCloned(false), isInvertedBranch(false), sharedBailOutKind(true), isLoopTopBailOutInfo(false),
+        totalOutParamCount(0), argOutSyms(nullptr), bailOutRecord(nullptr), wasCloned(false), isInvertedBranch(false), sharedBailOutKind(true), isLoopTopBailOutInfo(false), canDeadStore(true),
         outParamInlinedArgSlot(nullptr), liveVarSyms(nullptr), liveLosslessInt32Syms(nullptr), liveFloat64Syms(nullptr),
         branchConditionOpnd(nullptr),
         stackLiteralBailOutInfoCount(0), stackLiteralBailOutInfo(nullptr)
@@ -69,6 +69,7 @@ class BailOutInfo
 #endif
     bool wasCloned;
     bool isInvertedBranch;
+    bool canDeadStore;
     bool sharedBailOutKind;
     bool isLoopTopBailOutInfo;

lib/Backend/Func.cpp+9 −0 modified

@@ -345,6 +345,9 @@ Func::Codegen(JitArenaAllocator *alloc, JITTimeWorkItem * workItem,
             case RejitReason::TrackIntOverflowDisabled:
                 outputData->disableTrackCompoundedIntOverflow = TRUE;
                 break;
+            case RejitReason::MemOpDisabled:
+                outputData->disableMemOp = TRUE;
+                break;
             default:
                 Assume(UNREACHED);
             }
@@ -1124,6 +1127,12 @@ Func::IsTrackCompoundedIntOverflowDisabled() const
     return (HasProfileInfo() && GetReadOnlyProfileInfo()->IsTrackCompoundedIntOverflowDisabled()) || m_output.IsTrackCompoundedIntOverflowDisabled();
 }
 
+bool
+Func::IsMemOpDisabled() const
+{
+    return (HasProfileInfo() && GetReadOnlyProfileInfo()->IsMemOpDisabled()) || m_output.IsMemOpDisabled();
+}
+
 bool
 Func::IsArrayCheckHoistDisabled() const
 {

lib/Backend/Func.h+1 −0 modified

@@ -995,6 +995,7 @@ static const unsigned __int64 c_debugFillPattern8 = 0xcececececececece;
     void SetScopeObjSym(StackSym * sym);
     StackSym * GetScopeObjSym();
     bool IsTrackCompoundedIntOverflowDisabled() const;
+    bool IsMemOpDisabled() const;
     bool IsArrayCheckHoistDisabled() const;
     bool IsStackArgOptDisabled() const;
     bool IsSwitchOptDisabled() const;

lib/Backend/GlobOptBlockData.cpp+7 −5 modified

@@ -974,7 +974,8 @@ GlobOptBlockData::MergeValueInfo(
                 fromDataValueInfo->AsArrayValueInfo(),
                 fromDataSym,
                 symsRequiringCompensation,
-                symsCreatedForMerge);
+                symsCreatedForMerge,
+                isLoopBackEdge);
     }
 
     // Consider: If both values are VarConstantValueInfo with the same value, we could
@@ -1072,7 +1073,8 @@ ValueInfo *GlobOptBlockData::MergeArrayValueInfo(
     const ArrayValueInfo *const fromDataValueInfo,
     Sym *const arraySym,
     BVSparse<JitArenaAllocator> *const symsRequiringCompensation,
-    BVSparse<JitArenaAllocator> *const symsCreatedForMerge)
+    BVSparse<JitArenaAllocator> *const symsCreatedForMerge,
+    bool isLoopBackEdge)
 {
     Assert(mergedValueType.IsAnyOptimizedArray());
     Assert(toDataValueInfo);
@@ -1095,7 +1097,7 @@ ValueInfo *GlobOptBlockData::MergeArrayValueInfo(
         }
         else
         {
-            if (!this->globOpt->IsLoopPrePass())
+            if (!this->globOpt->IsLoopPrePass() && !isLoopBackEdge)
             {
                 // Adding compensation code in the prepass won't help, as the symstores would again be different in the main pass.
                 Assert(symsRequiringCompensation);
@@ -1123,7 +1125,7 @@ ValueInfo *GlobOptBlockData::MergeArrayValueInfo(
         }
         else
         {
-            if (!this->globOpt->IsLoopPrePass())
+            if (!this->globOpt->IsLoopPrePass() && !isLoopBackEdge)
             {
                 Assert(symsRequiringCompensation);
                 symsRequiringCompensation->Set(arraySym->m_id);
@@ -1150,7 +1152,7 @@ ValueInfo *GlobOptBlockData::MergeArrayValueInfo(
         }
         else
         {
-            if (!this->globOpt->IsLoopPrePass())
+            if (!this->globOpt->IsLoopPrePass() && !isLoopBackEdge)
             {
                 Assert(symsRequiringCompensation);
                 symsRequiringCompensation->Set(arraySym->m_id);

lib/Backend/GlobOptBlockData.h+1 −1 modified

@@ -264,7 +264,7 @@ class GlobOptBlockData
     Value *                 MergeValues(Value *toDataValue, Value *fromDataValue, Sym *fromDataSym, bool isLoopBackEdge, BVSparse<JitArenaAllocator> *const symsRequiringCompensation, BVSparse<JitArenaAllocator> *const symsCreatedForMerge);
     ValueInfo *             MergeValueInfo(Value *toDataVal, Value *fromDataVal, Sym *fromDataSym, bool isLoopBackEdge, bool sameValueNumber, BVSparse<JitArenaAllocator> *const symsRequiringCompensation, BVSparse<JitArenaAllocator> *const symsCreatedForMerge);
     JsTypeValueInfo *       MergeJsTypeValueInfo(JsTypeValueInfo * toValueInfo, JsTypeValueInfo * fromValueInfo, bool isLoopBackEdge, bool sameValueNumber);
-    ValueInfo *             MergeArrayValueInfo(const ValueType mergedValueType, const ArrayValueInfo *const toDataValueInfo, const ArrayValueInfo *const fromDataValueInfo, Sym *const arraySym, BVSparse<JitArenaAllocator> *const symsRequiringCompensation, BVSparse<JitArenaAllocator> *const symsCreatedForMerge);
+    ValueInfo *             MergeArrayValueInfo(const ValueType mergedValueType, const ArrayValueInfo *const toDataValueInfo, const ArrayValueInfo *const fromDataValueInfo, Sym *const arraySym, BVSparse<JitArenaAllocator> *const symsRequiringCompensation, BVSparse<JitArenaAllocator> *const symsCreatedForMerge, bool isLoopBackEdge);
 
     // Argument Tracking
 public:

lib/Backend/GlobOpt.cpp+15 −2 modified

@@ -2624,7 +2624,7 @@ GlobOpt::OptInstr(IR::Instr *&instr, bool* isInstrRemoved)
         !(instr->IsJitProfilingInstr()) &&
         this->currentBlock->loop && !IsLoopPrePass() &&
         !func->IsJitInDebugMode() &&
-        (func->HasProfileInfo() && !func->GetReadOnlyProfileInfo()->IsMemOpDisabled()) &&
+        !func->IsMemOpDisabled() &&
         this->currentBlock->loop->doMemOp)
     {
         CollectMemOpInfo(instrPrev, instr, src1Val, src2Val);
@@ -16531,6 +16531,7 @@ GlobOpt::GenerateBailOutMarkTempObjectIfNeeded(IR::Instr * instr, IR::Opnd * opn
         if (instr->HasBailOutInfo())
         {
             instr->SetBailOutKind(instr->GetBailOutKind() | IR::BailOutMarkTempObject);
+            instr->GetBailOutInfo()->canDeadStore = false;
         }
         else
         {
@@ -16540,6 +16541,11 @@ GlobOpt::GenerateBailOutMarkTempObjectIfNeeded(IR::Instr * instr, IR::Opnd * opn
                 || (instr->m_opcode == Js::OpCode::FromVar && !opnd->GetValueType().IsPrimitive())
                 || propertySymOpnd == nullptr
                 || !propertySymOpnd->IsTypeCheckProtected())
+            {
+                this->GenerateBailAtOperation(&instr, IR::BailOutMarkTempObject);
+                instr->GetBailOutInfo()->canDeadStore = false;
+            }
+            else if (propertySymOpnd->MayHaveImplicitCall())
             {
                 this->GenerateBailAtOperation(&instr, IR::BailOutMarkTempObject);
             }
@@ -16680,7 +16686,14 @@ GlobOpt::GenerateInductionVariableChangeForMemOp(Loop *loop, byte unroll, IR::In
     }
     else
     {
-        uint size = (loopCount->LoopCountMinusOneConstantValue() + 1)  * unroll;
+        int32 loopCountMinusOnePlusOne;
+        int32 size;
+        if (Int32Math::Add(loopCount->LoopCountMinusOneConstantValue(), 1, &loopCountMinusOnePlusOne) ||
+            Int32Math::Mul(loopCountMinusOnePlusOne, unroll, &size))
+        {
+            throw Js::RejitException(RejitReason::MemOpDisabled);
+        }
+        Assert(size > 0);
         sizeOpnd = IR::IntConstOpnd::New(size, IRType::TyUint32, localFunc);
     }
     loop->memOpInfo->inductionVariableOpndPerUnrollMap->Add(unroll, sizeOpnd);

lib/Backend/GlobOptFields.cpp+8 −0 modified

@@ -410,6 +410,14 @@ GlobOpt::ProcessFieldKills(IR::Instr *instr, BVSparse<JitArenaAllocator> *bv, bo
         if (inGlobOpt)
         {
             KillObjectHeaderInlinedTypeSyms(this->currentBlock, false);
+            if (this->objectTypeSyms)
+            {
+                if (this->currentBlock->globOptData.maybeWrittenTypeSyms == nullptr)
+                {
+                    this->currentBlock->globOptData.maybeWrittenTypeSyms = JitAnew(this->alloc, BVSparse<JitArenaAllocator>, this->alloc);
+                }
+                this->currentBlock->globOptData.maybeWrittenTypeSyms->Or(this->objectTypeSyms);
+            }
         }
 
         // fall through

lib/Backend/JITOutput.cpp+6 −0 modified

@@ -65,6 +65,12 @@ JITOutput::IsTrackCompoundedIntOverflowDisabled() const
     return m_outputData->disableTrackCompoundedIntOverflow != FALSE;
 }
 
+bool
+JITOutput::IsMemOpDisabled() const
+{
+    return m_outputData->disableMemOp != FALSE;
+}
+
 bool
 JITOutput::IsArrayCheckHoistDisabled() const
 {

lib/Backend/JITOutput.h+1 −0 modified

@@ -22,6 +22,7 @@ class JITOutput
     void RecordXData(BYTE * xdata);
 #endif
     bool IsTrackCompoundedIntOverflowDisabled() const;
+    bool IsMemOpDisabled() const;
     bool IsArrayCheckHoistDisabled() const;
     bool IsStackArgOptDisabled() const;
     bool IsSwitchOptDisabled() const;

lib/Backend/NativeCodeGenerator.cpp+4 −0 modified

@@ -1234,6 +1234,10 @@ NativeCodeGenerator::CodeGen(PageAllocator * pageAllocator, CodeGenWorkItem* wor
         {
             body->GetAnyDynamicProfileInfo()->DisableTrackCompoundedIntOverflow();
         }
+        if (jitWriteData.disableMemOp)
+        {
+            body->GetAnyDynamicProfileInfo()->DisableMemOp();
+        }
     }
 
     if (jitWriteData.disableInlineApply)

lib/Backend/Opnd.cpp+5 −6 modified

@@ -962,7 +962,8 @@ PropertySymOpnd::IsObjectHeaderInlined() const
 bool
 PropertySymOpnd::ChangesObjectLayout() const
 {
-    JITTypeHolder cachedType = this->IsMono() ? this->GetType() : this->GetFirstEquivalentType();
+    JITTypeHolder cachedType = this->HasInitialType() ? this->GetInitialType() : 
+        this->IsMono() ? this->GetType() : this->GetFirstEquivalentType();
 
     JITTypeHolder finalType = this->GetFinalType();
 
@@ -987,13 +988,11 @@ PropertySymOpnd::ChangesObjectLayout() const
         // This is the case where the type transition actually occurs. (This is the only case that's detectable
         // during the loop pre-pass, since final types are not in place yet.)
 
-        Assert(cachedType != nullptr && Js::DynamicType::Is(cachedType->GetTypeId()));
-
-        const JITTypeHandler * cachedTypeHandler = cachedType->GetTypeHandler();
         const JITTypeHandler * initialTypeHandler = initialType->GetTypeHandler();
 
-        return cachedTypeHandler->GetInlineSlotCapacity() != initialTypeHandler->GetInlineSlotCapacity() ||
-            cachedTypeHandler->GetOffsetOfInlineSlots() != initialTypeHandler->GetOffsetOfInlineSlots();
+        // If no final type has been set in the forward pass, then we have no way of knowing how the object shape will evolve here.
+        // If the initial type is object-header-inlined, assume that the layout may change.
+        return initialTypeHandler->IsObjectHeaderInlinedTypeHandler();
     }
 
     return false;

lib/Backend/Opnd.h+2 −1 modified

@@ -1138,7 +1138,8 @@ class PropertySymOpnd sealed : public SymOpnd
     // fall back on live cache.  Similarly, for fixed method checks.
     bool MayHaveImplicitCall() const
     {
-        return !IsRootObjectNonConfigurableFieldLoad() && !UsesFixedValue() && (!IsTypeCheckSeqCandidate() || !IsTypeCheckProtected());
+        return !IsRootObjectNonConfigurableFieldLoad() && !UsesFixedValue() && (!IsTypeCheckSeqCandidate() || !IsTypeCheckProtected()
+            || (IsLoadedFromProto() && NeedsWriteGuardTypeCheck()));
     }
 
     // Is the instruction involving this operand part of a type check sequence? This is different from IsObjTypeSpecOptimized

lib/Common/ChakraCoreVersion.h+1 −1 modified

@@ -17,7 +17,7 @@
 // ChakraCore version number definitions (used in ChakraCore binary metadata)
 #define CHAKRA_CORE_MAJOR_VERSION 1
 #define CHAKRA_CORE_MINOR_VERSION 11
-#define CHAKRA_CORE_PATCH_VERSION 10
+#define CHAKRA_CORE_PATCH_VERSION 11
 #define CHAKRA_CORE_VERSION_RELEASE_QFE 0 // Redundant with PATCH_VERSION. Keep this value set to 0.
 
 // -------------

lib/JITIDL/JITTypes.h+10 −5 modified

@@ -838,37 +838,42 @@ typedef struct JITOutputIDL
     boolean disableStackArgOpt;
     boolean disableSwitchOpt;
     boolean disableTrackCompoundedIntOverflow;
-    boolean isInPrereservedRegion;
+    boolean disableMemOp;
 
+    boolean isInPrereservedRegion;
     boolean hasBailoutInstr;
-
     boolean hasJittedStackClosure;
+    IDL_PAD1(0)
 
     unsigned short pdataCount;
     unsigned short xdataSize;
 
     unsigned short argUsedForBranch;
+    IDL_PAD2(1)
 
     int localVarSlotsOffset; // FunctionEntryPointInfo only
+
     int localVarChangedOffset; // FunctionEntryPointInfo only
     unsigned int frameHeight;
 
-
     unsigned int codeSize;
     unsigned int throwMapOffset;
+
     unsigned int throwMapCount;
     unsigned int inlineeFrameOffsetArrayOffset;
-    unsigned int inlineeFrameOffsetArrayCount;
 
+    unsigned int inlineeFrameOffsetArrayCount;
     unsigned int propertyGuardCount;
+
     unsigned int ctorCachesCount;
+    X64_PAD4(2)
 
 #if TARGET_64
     CHAKRA_PTR xdataAddr;
 #elif defined(_M_ARM)
     unsigned int xdataOffset;
 #else
-    X86_PAD4(0)
+    X86_PAD4(3)
 #endif
     CHAKRA_PTR codeAddress;
     CHAKRA_PTR thunkAddress;

7f0d390ad77d

[CVE-2019-1062] Chakra JIT Type Confusion

https://github.com/chakra-core/ChakraCorePaul LeathersJun 6, 2019via ghsa

commit

1 file changed · +5 −6

lib/Backend/Opnd.cpp+5 −6 modified

@@ -962,7 +962,8 @@ PropertySymOpnd::IsObjectHeaderInlined() const
 bool
 PropertySymOpnd::ChangesObjectLayout() const
 {
-    JITTypeHolder cachedType = this->IsMono() ? this->GetType() : this->GetFirstEquivalentType();
+    JITTypeHolder cachedType = this->HasInitialType() ? this->GetInitialType() : 
+        this->IsMono() ? this->GetType() : this->GetFirstEquivalentType();
 
     JITTypeHolder finalType = this->GetFinalType();
 
@@ -987,13 +988,11 @@ PropertySymOpnd::ChangesObjectLayout() const
         // This is the case where the type transition actually occurs. (This is the only case that's detectable
         // during the loop pre-pass, since final types are not in place yet.)
 
-        Assert(cachedType != nullptr && Js::DynamicType::Is(cachedType->GetTypeId()));
-
-        const JITTypeHandler * cachedTypeHandler = cachedType->GetTypeHandler();
         const JITTypeHandler * initialTypeHandler = initialType->GetTypeHandler();
 
-        return cachedTypeHandler->GetInlineSlotCapacity() != initialTypeHandler->GetInlineSlotCapacity() ||
-            cachedTypeHandler->GetOffsetOfInlineSlots() != initialTypeHandler->GetOffsetOfInlineSlots();
+        // If no final type has been set in the forward pass, then we have no way of knowing how the object shape will evolve here.
+        // If the initial type is object-header-inlined, assume that the layout may change.
+        return initialTypeHandler->IsObjectHeaderInlinedTypeHandler();
     }
 
     return false;

Vulnerability mechanics

Generated on May 9, 2026. Inputs: CWE entries + fix-commit diffs from this CVE's patches. Citations validated against bundle.

References

github.com/advisories/GHSA-rh4p-g7x6-8pqgghsaADVISORY
nvd.nist.gov/vuln/detail/CVE-2019-1062ghsaADVISORY
github.com/chakra-core/ChakraCore/commit/75162b7f2d8ac2b37d17564e9c979ba1bae707e8ghsaWEB
github.com/chakra-core/ChakraCore/commit/7f0d390ad77d838cbb81d4586c83ec822f384ce8ghsaWEB
portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1062ghsax_refsource_MISCWEB

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cvss	0.455
epss	0.004
exploit	0.000
kev	0.000
patch	-0.070
ransomware	0.000