CVE-2026-68462: Linux kernel · bpf: Reject negative const offsets for buffer pointers
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 7.8 High.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 17 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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
AI-suggested
A fix has been implemented in the Linux kernel to reject negative constant offsets for buffer pointers in the BPF verifier. Users should apply the official kernel updates that include this patch once available.
Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject negative const offsets for buffer pointers The verifier rejects variable offsets for PTR_TO_TP_BUFFER and PTR_TO_BUF accesses, but it currently accepts a constant negative offset produced by pointer arithmetic. Commit 022ac0750883 ("bpf: use reg->var_off instead of reg->off for pointers") moved constant pointer offsets from reg->off to reg->var_off. However, __check_buffer_access() continued to check only the instruction offset. An access with reg->var_off equal to -8 and an instruction offset of zero therefore passes verification. For writable raw tracepoints, the access end is also calculated from the unsigned reg->var_off.value. An eight-byte access starting at -8 wraps the calculated end to zero, allowing the program to load and attach without increasing max_tp_access. After ensuring that reg->var_off is constant, calculate the effective access start using signed arithmetic and reject it when it is negative. Use the validated start to calculate the access end for both PTR_TO_TP_BUFFER and PTR_TO_BUF.
References
- nvd.nist.gov/vuln/detail/CVE-2026-68462 (opens in a new tab)
- git.kernel.org/stable/c/314bd592085c0720ef519f6edbc5f41440ff78d4 (opens in a new tab)
- git.kernel.org/stable/c/fd4cfa8c8f9a17cdec0539334d28754bc1d8a5d9 (opens in a new tab)
- ubuntu.com/security/CVE-2026-68462 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-68462 (opens in a new tab)
- git.kernel.org/linus/fd4cfa8c8f9a17cdec0539334d28754bc1d8a5d9 (opens in a new tab)