---
id: "CVE-2026-123609"
page: "https://infrastack.ai/live/CVE-2026-123609"
kind: "vulnerability"
aliases: ["CVE-2026-123609"]
title: "Rustls: Debug output of session values can leak TLS secrets to logs"
severity: "medium"
cvss: 4.1
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["package", "rust", "rustls", "tls"]
not_affected_if: ["default-session-store", "no-session-value-logging"]
published_at: "2026-11-08T02:16:56+00:00"
first_seen_at: "2026-11-08T02:21:14+00:00"
updated_at: "2026-11-08T02:26:44+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123609", "first_seen_at": "2026-11-08T02:21:14+00:00"}]
exploit_sources: []
---

# Rustls: Debug output of session values can leak TLS secrets to logs

Link for people: https://infrastack.ai/live/CVE-2026-123609 (this .md is for agents)

Rustls before 0.23.46 and 0.24.0-dev.1 before 0.24.0-dev.2 derive Debug formatting for client session values that hold secret key material. A custom ClientSessionStore that logs these values writes TLS 1.2 master secrets or TLS 1.3 resumption PSKs into log files, where anyone who reads the logs can take them.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the Rustls version in Cargo.lock for `rustls` at `0.23.x` below `0.23.46`, or `0.24.0-dev.1` below `0.24.0-dev.2`.
- Search your code for a custom `ClientSessionStore` implementation that logs `Tls12ClientSessionValue` or `Tls13ClientSessionValue` with Debug formatting (`{:?}`).

## Fix

- `rustls` `0.23.46` for the 0.23 line
- `rustls` `0.24.0-dev.2` for the 0.24 development line

## Timeline

- 2026-11-08T02:21:14+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123609

## Documents

- [advisory] Vendor advisory: github.com https://github.com/rustls/rustls/security/advisories/GHSA-c8m5-c952-6cm4
- [advisory] Third-party advisory: www.vulncheck.com 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

## From the sources

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.

---

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