CVE-2026-31680
Description
In the Linux kernel, the following vulnerability has been resolved:
net: ipv6: flowlabel: defer exclusive option free until RCU teardown
ip6fl_seq_show() walks the global flowlabel hash under the seq-file RCU read-side lock and prints fl->opt->opt_nflen when an option block is present.
Exclusive flowlabels currently free fl->opt as soon as fl->users drops to zero in fl_release(). However, the surrounding struct ip6_flowlabel remains visible in the global hash table until later garbage collection removes it and fl_free_rcu() finally tears it down.
A concurrent /proc/net/ip6_flowlabel reader can therefore race that early kfree() and dereference freed option state, triggering a crash in ip6fl_seq_show().
Fix this by keeping fl->opt alive until fl_free_rcu(). That matches the lifetime already required for the enclosing flowlabel while readers can still reach it under RCU.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected products
22cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*+ 7 more
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*range: >=3.9,<5.10.253
- cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:7.0:rc5:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:7.0:rc6:*:*:*:*:*:*
- (no CPE)
- osv-coords14 versionspkg:linux/kernelpkg:rpm/opensuse/dtb-aarch64&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-64kb&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-azure&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-default&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-default-base&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-docs&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-kvmsmall&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-obs-build&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-obs-qa&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-rt&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-source&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-syms&distro=openSUSE%20Leap%2016.0pkg:rpm/opensuse/kernel-zfcpdump&distro=openSUSE%20Leap%2016.0
>= 3.9.0, < 5.10.253+ 13 more
- (no CPE)range: >= 3.9.0, < 5.10.253
- (no CPE)range: < 6.12.0-160000.36.1
- (no CPE)range: < 6.12.0-160000.36.1
- (no CPE)range: < 6.12.0-160000.36.1
- (no CPE)range: < 6.12.0-160000.36.1
- (no CPE)range: < 6.12.0-160000.36.1.160000.2.17
- (no CPE)range: < 6.12.0-160000.36.1
- (no CPE)range: < 6.12.0-160000.36.1
- (no CPE)range: < 6.12.0-160000.36.1
- (no CPE)range: < 6.12.0-160000.36.1
- (no CPE)range: < 6.12.0-160000.36.1
- (no CPE)range: < 6.12.0-160000.36.1
- (no CPE)range: < 6.12.0-160000.36.1
- (no CPE)range: < 6.12.0-160000.36.1
Patches
Vulnerability mechanics
References
10- git.kernel.org/stable/c/3c54b66c83fb8fcbde8e6a7bf90b65856e39f827nvdPatch
- git.kernel.org/stable/c/414726b69921fe6355ae453f5b35e68dd078342anvdPatch
- git.kernel.org/stable/c/4b6798024f7b2d535f3db1002c760143cdbd1bd3nvdPatch
- git.kernel.org/stable/c/572ce62778519a7d4d1c15f55dd2e45a474133c4nvdPatch
- git.kernel.org/stable/c/5a6b15f861b7c1304949e3350d23490a5fe429fdnvdPatch
- git.kernel.org/stable/c/6c7fbdb8ffde6413640de7cfbd7c976c353e89f8nvdPatch
- git.kernel.org/stable/c/8027964931785cb73d520ac70a342a3dc16c249bnvdPatch
- git.kernel.org/stable/c/9ca562bb8e66978b53028fa32b1a190708e6a091nvdPatch
- cert-portal.siemens.com/productcert/html/ssa-019113.htmlnvd
- cert-portal.siemens.com/productcert/html/ssa-082556.htmlnvd
News mentions
1- Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFPCISA ICS Advisories