Use-after-free in Linux kernel - CVE-2026-31680
Published: April 25, 2026
Vulnerability identifier: #VU127873
CSH Severity: Low
CVSS v4.0: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear
CVE-ID: CVE-2026-31680
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vendor: Linux Foundation
Affected software:
Linux kernel
Linux kernel
Detailed vulnerability description
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in ip6fl_seq_show() when reading /proc/net/ip6_flowlabel concurrently with flowlabel release. A local user can trigger concurrent access to dereference freed option state and cause a denial of service.
The issue occurs because the flowlabel remains reachable through the global hash table under RCU after its option state has been freed.
How to mitigate CVE-2026-31680
Install security update from vendor's repository.
Sources
- https://git.kernel.org/stable/c/3c54b66c83fb8fcbde8e6a7bf90b65856e39f827
- https://git.kernel.org/stable/c/414726b69921fe6355ae453f5b35e68dd078342a
- https://git.kernel.org/stable/c/4b6798024f7b2d535f3db1002c760143cdbd1bd3
- https://git.kernel.org/stable/c/572ce62778519a7d4d1c15f55dd2e45a474133c4
- https://git.kernel.org/stable/c/5a6b15f861b7c1304949e3350d23490a5fe429fd
- https://git.kernel.org/stable/c/6c7fbdb8ffde6413640de7cfbd7c976c353e89f8
- https://git.kernel.org/stable/c/8027964931785cb73d520ac70a342a3dc16c249b
- https://git.kernel.org/stable/c/9ca562bb8e66978b53028fa32b1a190708e6a091