CVE-2026-53081
HIGH 7.8In the Linux kernel, the following vulnerability has been resolved: bpf: Enforce regsafe base id consistency for BPF_ADD_CONST scalars When regsafe() compares two scalar registers that both carry BPF_ADD_CONST, check_scalar_ids() maps their full compound id (aka base | BPF_ADD_CONST flag) as one idmap entry. However, it never verifies that the underlying base ids, that is, with the flag stripped are consistent with existing idmap mappings. This allows construction of two verifier states where the old state has R3 = R2 + 10 (both sharing base id A) while the current state has R3 = R4 + 10 (base id C, unrelated to R2). The idmap creates two independent entries: A->B (for R2) and A|flag->C|flag (for R3), without catching that A->C conflicts with A->B. State pruning then incorrectly succeeds. Fix this by additionally verifying base ID mapping consistency whenever BPF_ADD_CONST is set: after mapping the compound ids, also invoke check_ids() on the base IDs (flag bits stripped). This ensures that if A was already mapped to B from comparing the source register, any ADD_CONST derivative must also derive from B, not an unrelated C.
Severe if exploited (CVSS 7.8), but no known exploitation and low modeled probability. Patch on a normal cadence.
Exploitation likelihood
0.1%chance of exploitation in 30 days · 2nd percentile
Impact if exploited
7.8CVSS 3.1 · HIGH
- ConfidentialityHigh
- IntegrityHigh
- AvailabilityHigh
What an attacker needs
- ⚠Access: Requires local access to the host
- ⚠Privileges: Requires a low-privilege account
- ✓User interaction: No user interaction needed
- ✓Complexity: No special conditions — reliably repeatable
✓ lowers the bar for an attacker · ⚠ raises it
Affected
Products Linux Red Hat Enterprise Linux 10 Red Hat Enterprise Linux 9 Red Hat Enterprise Linux 6 Red Hat Enterprise Linux 7 Red Hat Enterprise Linux 8
Weakness (CWE)
- CWE-386
CVSS vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
References
Technical & other
- https://git.kernel.org/stable/c/13c02881e49aac4c82b261faa26db9edf2567231
- https://git.kernel.org/stable/c/691adf738817275368ed56311b7d798d617823a3
- https://git.kernel.org/stable/c/7d73c72cccac651acc891377a5e623e4021c6380
- https://git.kernel.org/stable/c/2f2ec8e7730e21fc9bd49e0de9cdd58213ea24d0
- https://access.redhat.com/security/cve/CVE-2026-53081
- https://bugzilla.redhat.com/show_bug.cgi?id=2492322
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53081.json