riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args (CVE-2026-90195) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-90195

riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args

Answer in brief

CVE-2026-90195 records a Unknown severity vulnerability in riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args. 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.

Published Sep 17, 2026Updated Sep 17, 2026Source checked Sep 17, 2026First seen by HOL Sep 17, 2026Material review Sep 17, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

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.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
Linux/Linuxgeneric	>=443574b033876c85a35de4c65c14f7fe092222b2 <555fc6f1caf00ce7005e732b688da26c0dc3c5c5 \|\| >=443574b033876c85a35de4c65c14f7fe092222b2 <801ae90f8ce099187e6224cec7d72d07a4df0324 \|\| >=443574b033876c85a35de4c65c14f7fe092222b2 <71dbd143be598954ae103feadd12692aeb0f2f88 \|\| >=443574b033876c85a35de4c65c14f7fe092222b2 <f2aaa621591093cfe8224a25ef2f04a3b1e304b0	555fc6f1caf00ce7005e732b688da26c0dc3c5c5, 801ae90f8ce099187e6224cec7d72d07a4df0324, 71dbd143be598954ae103feadd12692aeb0f2f88, f2aaa621591093cfe8224a25ef2f04a3b1e304b0
Linux/Linuxgeneric	6.9	Not reported

Recommended response

Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
Review the reported fix. Update Linux/Linux to 555fc6f1caf00ce7005e732b688da26c0dc3c5c5 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 17, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 17, 2026

Sources and claim methodology

Upstream source description

In the Linux kernel, the following vulnerability has been resolved: riscv, bpf: Fix missing sign-ext for signed 1-byte and 2-byte kfunc args On RV64, the ABI requires sign-extension for signed 1-byte and 2-byte kfunc args. However, the RV64 JIT currently does not perform sign-extension for such kfunc args. Before commit 7ce090afbf72 ("bpf: Infer zext_dst based on static register liveness analysis"), state pruning could potentially omit zero-extension of 32-bit subregisters, which inadvertently masked the above issue by making the args appear as if they had been properly sign-extended. After that commit, the problem is exposed, causing the kfunc_call/kfunc_call_test4 selftest to fail. Fix this by extending the existing sign-extension logic to handle signed 1-byte and 2-byte kfunc args as well.

Quoted source text, attributed separately from HOL analysis.