Vulnerability MediumRUSTSEC-2026-0346 · rustls
RUSTSEC-2026-0346: `Debug` impls for client session values expose TLS secrets
Short answerA security vulnerability in the rustls crate: `Debug` impls for client session values expose TLS secrets. Medium severity (CVSS 4.0). Fixed in 0.23.46: update to a fixed version.
| Crate | rustls |
|---|---|
| Type | Vulnerability (crypto-failure) |
| Affected versions | From 0.21.0 before 0.23.46. |
| Fixed in | 0.23.46 |
| Severity | Medium, CVSS 4.0 CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N |
| Published | 2026-10-14 |
| Last changed | 2026-10-14 |
| Also known as | GHSA-c8m5-c952-6cm4 |
What to do
- See which version you have:
cargo tree -i rustls(it also shows which of your dependencies pulls it in). - Update within your version requirement:
cargo update -p rustls. If the fix is a newer major or minor than your requirement allows, raise it in Cargo.toml (for examplerustls = "0.23.46") or update the dependency that pulls it in. - Check again with
cargo audit, or paste your Cargo.lock into our Cargo.toml checker.
Details from the advisory
The Debug implementations of Tls12ClientSessionValue and Tls13ClientSessionValue were derived, and so included the TLS 1.2 master secret or TLS 1.3 resumption PSK in their output.
Custom ClientSessionStore implementations that format these values with Debug (for example, when logging) could disclose these secrets to readers of the logs. This conflicts with rustls's key-material redaction policy.
Ordinary connection and built-in session cache Debug output is redacted and is not affected.
References
- Package: crates.io/crates/rustls
- Advisory: rustsec.org/advisories/RUSTSEC-2026-0346.html
- Web: github.com/rustls/rustls/pull/3299
From the RustSec Advisory Database (CC0-1.0) via the OSV export, downloaded Oct 24, 2026. Severity score computed from the published CVSS vector.
Other advisories for rustls
- Vulnerability HighRUSTSEC-2024-0336 · 2024-04-19`rustls::ConnectionCommon::complete_io` could fall into an infinite loop based on network input
- VulnerabilityRUSTSEC-2024-0399 · 2024-11-22rustls network-reachable panic in `Acceptor::accept`
- Vulnerability MediumRUSTSEC-2026-0285 · 2026-09-14TLS 1.3 handshake messages incorrectly accepted across encryption level boundaries
- Vulnerability LowRUSTSEC-2026-0347 · 2026-10-14Buffered application data sent to outer server after ECH rejection
- Vulnerability LowRUSTSEC-2026-0348 · 2026-10-14Brotli certificate decompression can allocate up to 1 GiB before authentication
- Vulnerability LowRUSTSEC-2026-0349 · 2026-10-14Unauthenticated ServerHello can downgrade later connections to classical key exchange
Up next
Same craterustls: security historyEvery advisory for this crate, and whether it is safe to use today.Read it next →Did this answer your question?