CVE-2026-98061

CVE CVE-2026-98061EUVD EUVD-2026-86714Published 2026-09-25T10:24:06.000Z

What the advisory describes

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject tail calls directly from callback frames A tail call from a non-zero frame is modeled as a return from that frame. The verifier makes R0 unknown and calls prepare_func_exit() for the taken branch. When the current frame is a synchronous callback, prepare_func_exit() enforces the callback return-value contract and marks R0 precise. Since the tail-call path synthesized R0 rather than deriving it from an instruction, precision backtracking reaches the callback-calling instruction with R0 still requested and triggers the "callback unexpected regs" verifier bug. A CAP_BPF task can therefore cause a WARN and an -EFAULT BPF_PROG_LOAD. Tail calls reachable from callbacks are already rejected later by check_max_stack_depth(). Reject a tail call made directly by a callback before constructing the inconsistent return state, using the existing diagnostic. Tail calls from ordinary subprograms keep their current behavior.

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 e3245f8990431950d20631c72236d4e8cb2dcde8 <96d31b28263c429a56e4de85bcf744a5c320b3a3; patch: 0; a6c22c91b6284e4713c0cf5b20ab3c9c71b77ae8 <617c8266e49f45747f71e74177646a63f72b7025; 6.19; e3245f8990431950d20631c72236d4e8cb2dcde8 <266aa4ad0b2e82397cd9045752c9bff03d98eddd; patch: 7.3-rc2; 6.18.2 <6.18.53; patch: 7.2.7; patch: 6.18.53

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

Patchlage reports hits and suspected hits. About everything else this system says nothing — neither this page nor the situation report ever claims that an estate is safe.