CVE-2026-98038

CVE CVE-2026-98038EUVD EUVD-2026-86691Published 2026-09-25T10:23:51.000Z

What the advisory describes

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 ]

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

• Linux — Linux patch: 7.2.7; patch: 7.3-rc2; 1b12171533a9bb23cf6fba7262b479028b65e1e8 <dc36739e5cc9f60485418a910b42bc95339218d2; patch: 0; 6.8; 1b12171533a9bb23cf6fba7262b479028b65e1e8 <85074498228a2500ea8b8039c49cc1ab8ad5328f

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

An estate covering these products can be recorded in Patchlage. An advisory about them appears in the next morning's situation report.

• Linux — Linux

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