---
id: "CVE-2026-123613"
page: "https://infrastack.ai/live/CVE-2026-123613"
kind: "vulnerability"
aliases: ["CVE-2026-123613"]
title: "Rustls: TLS 1.3 handshake messages accepted unencrypted, letting on-path attackers inject"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["cargo", "package", "rust", "rustls", "tls"]
not_affected_if: ["no-rustls-usage", "version-outside-range"]
published_at: "2026-11-08T02:16:56+00:00"
first_seen_at: "2026-11-08T02:21:14+00:00"
updated_at: "2026-11-08T02:24:41+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-123613", "first_seen_at": "2026-11-08T02:21:14+00:00"}]
exploit_sources: []
---

# Rustls: TLS 1.3 handshake messages accepted unencrypted, letting on-path attackers inject

Link for people: https://infrastack.ai/live/CVE-2026-123613 (this .md is for agents)

Rustls accepts TLS 1.3 handshake messages at the wrong encryption level when they follow a key-changing message in the same record, because record-boundary alignment is not enforced. A peer or on-path attacker can place a plaintext EncryptedExtensions message alongside the ServerHello, and rustls accepts it unencrypted.

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

## How to check

- Find the `rustls` version in `Cargo.lock` or `cargo tree` output for each service.
- Flag any version from `0.23.13` up to but not including `0.23.45`.
- Check whether the TLS client or server path uses rustls at all, since only TLS 1.3 handshakes are described.

## Fix

- `rustls` `0.23.45` (fixed version for the 0.23.x line, per the affected range 0.23.13 to before 0.23.45)

## Timeline

- 2026-11-08T02:21:14+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-123613

## Documents

- [advisory] Vendor advisory: github.com https://github.com/rustls/rustls/security/advisories/GHSA-2mjx-qc3c-rqvc
- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/rustls-0.23.13-before-0.23.45-tls-1.3-handshake-encryption-level-bypass
- [fix] Patch: github.com https://github.com/rustls/rustls/commit/5046bdf8a612b35a2c1a9e168054c1d5c65e7dd7

## From the sources

Rustls from 0.23.13 before 0.23.45 accepts TLS 1.3 handshake messages at the wrong encryption level when they follow a key-changing message in the same record, because Deframer::aligned does not enforce RFC 8446 record-boundary alignment. A peer or on-path attacker can pack a plaintext EncryptedExtensions with the ServerHello, which rustls accepts unencrypted.

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