Critical severityNVD Advisory· Published Dec 4, 2023· Updated Aug 2, 2024

Improper Sanitization of Branch Name Leads to Arbitrary Code Injection

CVE-2023-49291

Description

The tj-actions/branch-names GitHub Action is vulnerable to remote code execution via specially crafted branch names, enabling secret theft and unauthorized GitHub token abuse.

AI Insight

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

The tj-actions/branch-names GitHub Action is vulnerable to remote code execution via specially crafted branch names, enabling secret theft and unauthorized GitHub token abuse.

Root

Cause

The tj-actions/branch-names GitHub Action is a composite action that retrieves branch or tag names during CI/CD workflows. A command injection vulnerability exists because the action improperly expands the github.event.pull_request.head.ref and github.head_ref context variables directly within a run step (shell: bash). Prior to version 7.0.7, these user-controlled variables were interpolated into the script without proper sanitization, allowing an attacker to inject arbitrary commands through a specially crafted branch name [1][2].

Attack

Vector

An attacker can exploit this vulnerability by creating a pull request with a malicious branch name containing shell metacharacters (e.g., backticks or $()). When a GitHub Actions workflow uses tj-actions/branch-names on that pull request (e.g., in response to pull_request_target or any trigger where the head ref is trusted), the injected commands execute in the runner context. No authentication beyond the ability to open a pull request against the repository is required; however, the victim repository must have a workflow that uses an affected version of the action [1].

Impact

Successful exploitation allows an attacker to execute arbitrary shell commands with the privileges of the GITHUB_TOKEN. This can result in exfiltration of repository secrets, unauthorized modifications to the repository, or compromise of downstream CI/CD pipelines. The injected commands run in the same environment that processes the action, giving the attacker full access to the runner's secrets and token permissions [1][2].

Mitigation

The vulnerability is fixed in version 7.0.7. The fix moves the use of context variables into environment variables before passing them to the run step, preventing direct command interpolation. The commit 4923d1c and subsequent hardening commit 6c999ac demonstrate this change. Users must update their workflow pin from @v7 or earlier to @v7.0.7 or later. No workarounds exist; upgrading is the only mitigation [1][2][3][4].

References

AI Insight generated on May 20, 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
tj-actions/branch-namesGitHub Actions	< 7.0.7	7.0.7

Affected products

ghsa-coords
pkg:github/tj-actions/branch-names
Range: < 7.0.7
Tj Actions/Branch Namescpe-rescue
Range: < 7.0.7

Patches

6c999acf206f

Merge pull request #272 from tj-actions/security/remove-vulnerable-events-from-test

https://github.com/tj-actions/branch-namesrepo-ranger[bot]Dec 3, 2023via ghsa

commit

1 file changed · +0 −2

.github/workflows/test.yml+0 −2 modified

@@ -8,8 +8,6 @@ on:
       - main
   release:
     types: [published, created]
-  pull_request_review:
-  pull_request_target:
   pull_request:
     branches:
       - main

726fe9ba5e9d

security: remove vulnerable events from test

https://github.com/tj-actions/branch-namesTonye JackDec 3, 2023via ghsa

commit

1 file changed · +0 −2

.github/workflows/test.yml+0 −2 modified

@@ -8,8 +8,6 @@ on:
       - main
   release:
     types: [published, created]
-  pull_request_review:
-  pull_request_target:
   pull_request:
     branches:
       - main

4923d1ca41f9

Merge pull request #271 from tj-actions/security/prevent-arbitrary-code-injection-via-untrusted-inputs

https://github.com/tj-actions/branch-namesrepo-ranger[bot]Dec 3, 2023via ghsa

commit

1 file changed · +36 −17

action.yml+36 −17 modified

@@ -37,12 +37,18 @@ runs:
   using: "composite"
   steps:
     - id: branch
+      env:
+        GITHUB_REF: ${{ github.ref }}
+        GITHUB_BASE_REF: ${{ github.event.pull_request.base.ref || github.base_ref }}
+        GITHUB_HEAD_REF: ${{ github.event.pull_request.head.ref || github.head_ref }}
+        GITHUB_EVENT_BASE_REF: ${{ github.event.base_ref }}
+        INPUTS_STRIP_TAG_PREFIX: ${{ inputs.strip_tag_prefix }}
       run: |
         # "Set branch names..."
-        if [[ "${{ github.ref }}" != "refs/tags/"* ]]; then
-          BASE_REF=$(printf "%q" "${{ github.event.pull_request.base.ref || github.base_ref }}")
-          HEAD_REF=$(printf "%q" "${{ github.event.pull_request.head.ref || github.head_ref }}")
-          REF=$(printf "%q" "${{ github.ref }}")
+        if [[ "$GITHUB_REF" != "refs/tags/"* ]]; then
+          BASE_REF=$(printf "%q" "$GITHUB_BASE_REF")
+          HEAD_REF=$(printf "%q" "$GITHUB_HEAD_REF")
+          REF=$(printf "%q" "$GITHUB_REF")
 
           BASE_REF=${BASE_REF/refs\/heads\//}
           HEAD_REF=${HEAD_REF/refs\/heads\//}
@@ -53,42 +59,55 @@ runs:
           echo "head_ref_branch=$(eval printf "%s" "$HEAD_REF")" >> "$GITHUB_OUTPUT"
           echo "ref_branch=$(eval printf "%s" "$REF_BRANCH")" >> "$GITHUB_OUTPUT"
         else
-          BASE_REF=$(printf "%q" "${{ github.event.base_ref }}")
-          BASE_REF=${BASE_REF/refs\/heads\/${{ inputs.strip_tag_prefix }}/}
+          BASE_REF=$(printf "%q" "$GITHUB_EVENT_BASE_REF")
+          BASE_REF=${BASE_REF/refs\/heads\/$INPUTS_STRIP_TAG_PREFIX/}
           
           echo "base_ref_branch=$(eval printf "%s" "$BASE_REF")" >> "$GITHUB_OUTPUT"
         fi
       shell: bash
     - id: current_branch
+      env:
+        GITHUB_REF: ${{ github.ref }}
+        GITHUB_EVENT_NAME: ${{ github.event_name }}
+        HEAD_REF_BRANCH: ${{ steps.branch.outputs.head_ref_branch }}
+        REF_BRANCH: ${{ steps.branch.outputs.ref_branch }}
       run: |
         # "Set the current branch name..."
-        if [[ "${{ github.ref }}" != "refs/tags/"* ]]; then
-          if [[ ${{ github.event_name }} == *"pull_request"* ]]; then
-            echo "current_branch=${{ steps.branch.outputs.head_ref_branch }}" >> "$GITHUB_OUTPUT"
+        if [[ "$GITHUB_REF" != "refs/tags/"* ]]; then
+          if [[ "$GITHUB_EVENT_NAME" == *"pull_request"* ]]; then
+            echo "current_branch=$HEAD_REF_BRANCH" >> "$GITHUB_OUTPUT"
           else
-            echo "current_branch=${{ steps.branch.outputs.ref_branch }}" >> "$GITHUB_OUTPUT"
+            echo "current_branch=$REF_BRANCH" >> "$GITHUB_OUTPUT"
           fi
         fi
       shell: bash
     - id: default
+      env:
+        GITHUB_REF: ${{ github.ref }}
+        CURRENT_BRANCH: ${{ steps.current_branch.outputs.current_branch }}
+        DEFAULT_BRANCH: ${{ github.event.repository.default_branch }}
+        FORK: ${{ github.event.pull_request.head.repo.fork }}
       run: |
         # "Set the default branch name..."
-        if [[ "${{ github.ref }}" != "refs/tags/"* ]]; then
-          if [[ "${{ steps.current_branch.outputs.current_branch }}" == "${{ github.event.repository.default_branch }}" && "${{ github.event.pull_request.head.repo.fork }}" != "true" ]]; then
+        if [[ "$GITHUB_REF" != "refs/tags/"* ]]; then
+          if [[ "$CURRENT_BRANCH" == "$DEFAULT_BRANCH" && "$FORK" != "true" ]]; then
             echo "is_default=true" >> "$GITHUB_OUTPUT"
-            echo "default_branch=${{ github.event.repository.default_branch }}" >> "$GITHUB_OUTPUT"
+            echo "default_branch=$DEFAULT_BRANCH" >> "$GITHUB_OUTPUT"
           else
             echo "is_default=false" >> "$GITHUB_OUTPUT"
-            echo "default_branch=${{ github.event.repository.default_branch }}" >> "$GITHUB_OUTPUT"
+            echo "default_branch=$DEFAULT_BRANCH" >> "$GITHUB_OUTPUT"
           fi
         fi
       shell: bash
     - id: tag
+      env:
+        GITHUB_REF: ${{ github.ref }}
+        INPUTS_STRIP_TAG_PREFIX: ${{ inputs.strip_tag_prefix }}
       run: |
         # "Set the tag name..."
-        if [[ "${{ github.ref }}" == "refs/tags/"* ]]; then
-          REF=$(printf "%q" "${{ github.ref }}")
-          TAG=${REF/refs\/tags\/${{ inputs.strip_tag_prefix }}/}
+        if [[ "$GITHUB_REF" == "refs/tags/"* ]]; then
+          REF=$(printf "%q" "$GITHUB_REF")
+          TAG="${REF/refs\/tags\/$INPUTS_STRIP_TAG_PREFIX/}"
 
           echo "tag=$(eval printf "%s" "$TAG")" >> "$GITHUB_OUTPUT"
           echo "is_tag=true" >> "$GITHUB_OUTPUT"

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-8v8w-v8xg-79rfghsaADVISORY
nvd.nist.gov/vuln/detail/CVE-2023-49291ghsaADVISORY
github.com/tj-actions/branch-names/commit/4923d1ca41f928c24f1c1b3af9daaadfb71e6337ghsax_refsource_MISCWEB
github.com/tj-actions/branch-names/commit/6c999acf206f5561e19f46301bb310e9e70d8815ghsax_refsource_MISCWEB
github.com/tj-actions/branch-names/commit/726fe9ba5e9da4fcc716223b7994ffd0358af060ghsax_refsource_MISCWEB
github.com/tj-actions/branch-names/security/advisories/GHSA-8v8w-v8xg-79rfghsax_refsource_CONFIRMWEB
securitylab.github.com/research/github-actions-untrusted-inputghsax_refsource_MISCWEB

News mentions

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cvss	0.585
epss	0.001
exploit	0.000
kev	0.000
patch	-0.070
ransomware	0.000