Rust advisories / ws
Vulnerability HighRUSTSEC-2020-0043 · ws
RUSTSEC-2020-0043: Insufficient size checks in outgoing buffer in ws allows remote attacker to run the process out of memory
Short answerA security vulnerability in the ws crate: Insufficient size checks in outgoing buffer in ws allows remote attacker to run the process out of memory. High severity (CVSS 7.5). No fixed version: replace the crate or remove the affected code path.
| Crate | ws |
|---|---|
| Type | Vulnerability (denial-of-service) |
| Affected versions | Every version. |
| Fixed in | none |
| Severity | High, CVSS 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| Published | 2020-09-25 |
| Last changed | 2023-11-08 |
| Also known as | CVE-2020-35896, GHSA-rh7x-ppxx-p34c |
What to do
- Find who pulls it in:
cargo tree -i ws. - Avoid the affected API, or replace the crate.
Details from the advisory
Affected versions of this crate did not properly check and cap the growth of the outgoing buffer.
This allows a remote attacker to take down the process by growing the buffer of their (single) connection until the process runs out of memory it can allocate and is killed.
The flaw was corrected in the parity-ws fork (>=0.10.0) by disconnecting a client when the buffer runs full.
References
- Package: crates.io/crates/ws
- Advisory: rustsec.org/advisories/RUSTSEC-2020-0043.html
- Report: github.com/housleyjk/ws-rs/issues/291
From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.
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