CVE-2025-38591bpf: Reject narrower access to pointer ctx fields
- 5.5MediumCVSS base score
- 0.22%Exploitation in 30 daysEPSS · top 87% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: bpf: Reject narrower access to pointer ctx fields The following BPF program, simplified from a syzkaller repro, causes a kernel warning: r0 = *(u8 *)(r1 + 169); exit; With pointer field sk being at offset 168 in __sk_buff. This access is detected as a narrower read in bpf_skb_is_valid_access because it doesn't match offsetof(struct __sk_buff, sk). It is therefore allowed and later proceeds to bpf_convert_ctx_access. Note that for the "is_narrower_load" case in the convert_ctx_accesses(), the insn->off is aligned, so the cnt may not be 0 because it matches the offsetof(struct __sk_buff, sk) in the bpf_convert_ctx_access. However, the target_size stays 0 and the verifier errors with a kernel warning: verifier bug: error during ctx access conversion(1) This patch fixes that to return a proper "invalid bpf_context access off=X size=Y" error on the load instruction. The same issue affects multiple other fields in context structures that allow narrow access. Some other non-affected fields (for sk_msg, sk_lookup, and sockopt) were also changed to use bpf_ctx_range_ptr for consistency. Note this syzkaller crash was reported in the "Closes" link below, which used to be about a different bug, fixed in commit fce7bd8e385a ("bpf/verifier: Handle BPF_LOAD_ACQ instructions in insn_def_regno()"). Because syzbot somehow confused the two bugs, the new crash and repro didn't get reported to the mailing list.
Timeline
ID reserved
By Linux
- 4 months later
· 4 months later
Published
- 15 months later
· 15 months later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Medium5.5 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 0.22% · top 87% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 5.5.
Affected products
- affected f96da09473b52c09125cc9bf7d7d4576ae8229e0 – < 7847c4140e06f6e87229faae22cc38525334c156
- affected f96da09473b52c09125cc9bf7d7d4576ae8229e0 – < feae34c992eb7191862fb1594c704fbbf650fef8
- affected f96da09473b52c09125cc9bf7d7d4576ae8229e0 – < 33660d44e789edb4f303210c813fc56d56377a90
- affected f96da09473b52c09125cc9bf7d7d4576ae8229e0 – < e2e9599f3503df7cf3569d2b6c50d5488fb59435
- affected f96da09473b52c09125cc9bf7d7d4576ae8229e0 – < 058a0da4f6d916a79b693384111bb80a90d73763
- affected f96da09473b52c09125cc9bf7d7d4576ae8229e0 – < 202900ceeef67458c964c2af6e1427c8e533ea7c
- affected f96da09473b52c09125cc9bf7d7d4576ae8229e0 – < e09299225d5ba3916c91ef70565f7d2187e4cca0
- affected 4.13
- unaffected < 4.13
- unaffected 5.10.249 – ≤ 5.10.*
- unaffected 5.15.199 – ≤ 5.15.*
- unaffected 6.1.162 – ≤ 6.1.*
- unaffected 6.6.157 – ≤ 6.6.*
- unaffected 6.12.67 – ≤ 6.12.*
- unaffected 6.16.1 – ≤ 6.16.*
- unaffected 6.17 – ≤ *
References
References9
- https://git.kernel.org/stable/c/7847c4140e06f6e87229faae22cc38525334c156 (opens in a new tab)
- https://git.kernel.org/stable/c/feae34c992eb7191862fb1594c704fbbf650fef8 (opens in a new tab)
- https://git.kernel.org/stable/c/33660d44e789edb4f303210c813fc56d56377a90 (opens in a new tab)
- https://git.kernel.org/stable/c/e2e9599f3503df7cf3569d2b6c50d5488fb59435 (opens in a new tab)
- https://git.kernel.org/stable/c/058a0da4f6d916a79b693384111bb80a90d73763 (opens in a new tab)
- https://git.kernel.org/stable/c/202900ceeef67458c964c2af6e1427c8e533ea7c (opens in a new tab)
- https://git.kernel.org/stable/c/e09299225d5ba3916c91ef70565f7d2187e4cca0 (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2025-27920 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2025-38591)Record last updated .