CVE-2026-98038bpf: Keep refcount_acquire nullable for borrowed RCU kptrs
- —Not scoredno CVSS score yet
- 0.21%Exploitation in 30 daysEPSS · top 88% 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: Keep refcount_acquire nullable for borrowed RCU kptrs bpf_refcount_acquire() is fallible for a borrowed reference because the object may have reached a zero refcount. The verifier therefore keeps KF_RET_NULL on the return value unless the argument is an owning reference. An RCU-protected load of a local kptr is marked MEM_ALLOC, but it only receives NON_OWN_REF when the pointee contains a graph node. A refcounted object without a graph node consequently looks like an owning reference even though the loaded register has no acquired reference state. If the program drops the last real reference while remaining in the RCU critical section, refcount_inc_not_zero() returns NULL while the verifier treats the result as non-NULL. Only classify the argument as owning when it is backed by a verifier-tracked reference. This retains the non-NULL return for pointers from bpf_obj_new(), bpf_kptr_xchg(), or an earlier successful acquisition, while requiring a NULL check for borrowed RCU kptrs. [ kkd: Rewrote commit log ]
Timeline
ID reserved
By Linux
Published
- 26 days later
· 26 days 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
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.21% · top 88% of all CVEs (13 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected 1b12171533a9bb23cf6fba7262b479028b65e1e8 – < 85bfc8b6db43502444c428eaa2de20bdd2fb9064
- affected 1b12171533a9bb23cf6fba7262b479028b65e1e8 – < 8d19e2cdfba9ba8c8eb6a459cd666bec00a1d2c6
- affected 1b12171533a9bb23cf6fba7262b479028b65e1e8 – < 85074498228a2500ea8b8039c49cc1ab8ad5328f
- affected 1b12171533a9bb23cf6fba7262b479028b65e1e8 – < dc36739e5cc9f60485418a910b42bc95339218d2
- affected 6.8
- unaffected < 6.8
- unaffected 6.12.114 – ≤ 6.12.*
- unaffected 6.18.57 – ≤ 6.18.*
- unaffected 7.2.7 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References4
- https://git.kernel.org/stable/c/85bfc8b6db43502444c428eaa2de20bdd2fb9064 (opens in a new tab)
- https://git.kernel.org/stable/c/8d19e2cdfba9ba8c8eb6a459cd666bec00a1d2c6 (opens in a new tab)
- https://git.kernel.org/stable/c/85074498228a2500ea8b8039c49cc1ab8ad5328f (opens in a new tab)
- https://git.kernel.org/stable/c/dc36739e5cc9f60485418a910b42bc95339218d2 (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-2026-86691 (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-2026-98038)Record last updated .