Skip to main content
VulnerabilityPublished Updated

CVE-2026-53081: Linux kernel · bpf: Enforce regsafe base id consistency for BPF_ADD_CONST scalars

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in 691adf738817275368ed56311b7d798d617823a3 : patch Linux kernel soon.

Data as of 26 Oct 2026, 16:53 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
Exploitation
No evidence of active exploitation and no public proof of concept
Automatable
Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in 691adf738817275368ed56311b7d798d617823a3, 13c02881e49aac4c82b261faa26db9edf2567231, 7d73c72cccac651acc891377a5e623e4021c6380 +1
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade Linux kernel to 691adf738817275368ed56311b7d798d617823a3, 13c02881e49aac4c82b261faa26db9edf2567231, 7d73c72cccac651acc891377a5e623e4021c6380 or 2f2ec8e7730e21fc9bd49e0de9cdd58213ea24d0.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 98d7ca374ba4b39e7535613d40e159f09ca14da2, < 691adf738817275368ed56311b7d798d617823a3
Fixed in
  • 691adf738817275368ed56311b7d798d617823a3
LinuxLinuxAffected
  • ≥ 98d7ca374ba4b39e7535613d40e159f09ca14da2, < 13c02881e49aac4c82b261faa26db9edf2567231
Fixed in
  • 13c02881e49aac4c82b261faa26db9edf2567231
LinuxLinuxAffected
  • ≥ 98d7ca374ba4b39e7535613d40e159f09ca14da2, < 7d73c72cccac651acc891377a5e623e4021c6380
Fixed in
  • 7d73c72cccac651acc891377a5e623e4021c6380
LinuxLinuxAffected
  • ≥ 98d7ca374ba4b39e7535613d40e159f09ca14da2, < 2f2ec8e7730e21fc9bd49e0de9cdd58213ea24d0
Fixed in
  • 2f2ec8e7730e21fc9bd49e0de9cdd58213ea24d0
LinuxLinuxAffected
  • =6.11
Fixed in–

Description

In 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.

References

Community reviews

Loading reviews…