CVE-2026-74305
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk3th percentile - higher than 3% of all known CVEs
Summary
In the Linux kernel, the BPF cookie compatibility check for program arrays is insufficient. A program without cgroup storage can be considered compatible with any storage cookie, allowing a bridge in a tail call chain between an entry program and a storage-using callee, leading to incorrect access to cgroup local storage.
Risk Assessment
The vulnerability may allow unauthorized access to data in cgroup storage, potentially leading to isolation breach and possibly privilege escalation.
Recommendation
Apply the Linux kernel patch that tightens cookie checks, accepting zero cookie only for programs that cannot perform tail calls themselves.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: bpf: Tighten cgroup storage cookie checks for prog arrays The fix in commit abad3d0bad72 ("bpf: Fix oob access in cgroup local storage") is still incomplete. The prog-array compatibility check treats a program with no cgroup storage as compatible with any stored storage cookie. This allows a storage-less program to bridge a tail call chain between an entry program and a storage-using callee even though cgroup local storage at runtime still follows the caller's context, that is, A -> B(no storage) -> C(storage) path. Requiring exact cookie equality would break the legitimate case of a storage-less leaf program being tail called from a storage-using one. Instead, only accept a zero storage cookie if the program cannot perform tail calls itself. This keeps A -> B(no storage) working while rejecting the A -> B(no storage) -> C(storage) bridge.