Answer in brief
CVE-2026-98061 records a Unknown severity vulnerability in bpf: Reject tail calls directly from callback frames. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=a6c22c91b6284e4713c0cf5b20ab3c9c71b77ae8 <617c8266e49f45747f71e74177646a63f72b7025 || >=e3245f8990431950d20631c72236d4e8cb2dcde8 <96d31b28263c429a56e4de85bcf744a5c320b3a3 || >=e3245f8990431950d20631c72236d4e8cb2dcde8 <266aa4ad0b2e82397cd9045752c9bff03d98eddd || >=6.18.2 <6.18.53 | 617c8266e49f45747f71e74177646a63f72b7025, 96d31b28263c429a56e4de85bcf744a5c320b3a3, 266aa4ad0b2e82397cd9045752c9bff03d98eddd, 6.18.53 |
| Linux/Linuxgeneric | 6.19 | Not reported |
Published upstream
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Sep 25, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Sep 25, 2026
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.
Quoted source text, attributed separately from HOL analysis.