What is CVE-2026-123609?

CVE-2026-123609 is a medium-severity vulnerability in Rustls, classified under Improper Removal of Sensitive Information Before Storage or Transfer. CVSS score: 4.0/10. Published 2026-11-08.

How severe is CVE-2026-123609?

Medium severity. CVSS v3 base score is 4.0 out of 10.

Vulnerability in Rustls

CVE-2026-123609

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.

Published 2026-11-08.

CVSS v3 metric

CVSS v3 base score 4.0 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:R/S:U/C:H/I:N/A:N.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Rustls

Weakness classification (CWE)

CWE-212 — Improper Removal of Sensitive Information Before Storage or Transfer

References

GitHub Security Advisory (GHSA-c8m5-c952-6cm4) (vendor-advisory)
VulnCheck Advisory: Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 Secret Exposure via Debug (third-party-advisory)

Frequently asked questions

What is CVE-2026-123609?: CVE-2026-123609 is a medium-severity vulnerability in Rustls, classified under Improper Removal of Sensitive Information Before Storage or Transfer. CVSS score: 4.0/10. Published 2026-11-08.
How severe is CVE-2026-123609?: Medium severity. CVSS v3 base score is 4.0 out of 10.