Answer in brief
CVE-2025-21666 records a Medium severity (CVSS 5.5) vulnerability in vsock: prevent null-ptr-deref in vsock_*[has_data|has_space]. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic), Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystem (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.5. 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), Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystem (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <daeac89cdb03d30028186f5ff7dc26ec8fa843e7 || >=c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <9e5fed46ccd2c34c5fa5a9c8825ce4823fdc853e || >=c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <b52e50dd4fabd12944172bd486a4f4853b7f74dd || >=c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <bc9c49341f9728c31fe248c5fbba32d2e81a092b || >=c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <c23d1d4f8efefb72258e9cedce29de10d057f8ca || >=c0cfa2d8a788fcf45df5bf4070ab2474c88d543a <91751e248256efc111e52e15115840c35d85abaf | daeac89cdb03d30028186f5ff7dc26ec8fa843e7, 9e5fed46ccd2c34c5fa5a9c8825ce4823fdc853e, b52e50dd4fabd12944172bd486a4f4853b7f74dd, bc9c49341f9728c31fe248c5fbba32d2e81a092b, c23d1d4f8efefb72258e9cedce29de10d057f8ca, 91751e248256efc111e52e15115840c35d85abaf |
| Linux/Linuxgeneric | 5.5 | Not reported |
| Siemens/SIMATIC S7-1500 TM MFP - GNU/Linux subsystemgeneric | >=0 <* | * |
Published upstream
Jan 31, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 15, 2026
In the Linux kernel, the following vulnerability has been resolved: vsock: prevent null-ptr-deref in vsock_*[has_data|has_space] Recent reports have shown how we sometimes call vsock_*_has_data() when a vsock socket has been de-assigned from a transport (see attached links), but we shouldn't. Previous commits should have solved the real problems, but we may have more in the future, so to avoid null-ptr-deref, we can return 0 (no space, no data available) but with a warning. This way the code should continue to run in a nearly consistent state and have a warning that allows us to debug future problems.
Quoted source text, attributed separately from HOL analysis.