# CVE-2026-123609: Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 Secret Exposure via Debug

Status: published. Published: 2026-11-08. Updated: 2026-11-08.

Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 contains an information disclosure vulnerability where derived Debug formatting of client session values exposes secret key material. Custom ClientSessionStore implementations that log Tls12ClientSessionValue or Tls13ClientSessionValue can leak TLS 1.2 master secrets or TLS 1.3 resumption PSKs to log readers.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- rustls / rustls (rustls): ≥ 0; < 0.23.46 (affected, semver); 0.23.46 (unaffected, semver); ≥ 0.24.0-dev.1; < 0.24.0-dev.2 (affected, semver); 0.24.0-dev.2 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 4.1 (medium); CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 4 (medium); CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-212

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/rustls/rustls/security/advisories/GHSA-c8m5-c952-6cm4 (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/rustls-before-0.23.46-and-0.24.0-dev.1-before-0.24.0-dev.2-secret-exposure-via-debug (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-123609; retrieved 2026-11-08; source updated 2026-11-08

Revision: eeb72027454b9a021521947c4f7e931d541d2f1e4e412f4271fa6b6d2e75bab4

Canonical: https://y2.dev/cve/CVE-2026-123609

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