CVE-2026-24904 (GCVE-0-2026-24904)

Vulnerability from cvelistv5 – Published: 2026-01-29 21:19 – Updated: 2026-01-29 21:34
VLAI
Title
TrustTunnel has `client_random_prefix` rule bypass via fragmented or partial TLS ClientHello
Summary
TrustTunnel is an open-source VPN protocol with a rule bypass issue in versions prior to 0.9.115. In `tls_listener.rs`, `TlsListener::listen()` peeks 1024 bytes and calls `extract_client_random(...)`. If `parse_tls_plaintext` fails (for example, a fragmented/partial ClientHello split across TCP writes), `extract_client_random` returns `None`. In `rules.rs`, `RulesEngine::evaluate` only evaluates `client_random_prefix` when `client_random` is `Some(...)`. As a result, when extraction fails (`client_random == None`), any rule that relies on `client_random_prefix` matching is skipped and evaluation falls through to later rules. As an important semantics note: `client_random_prefix` is a match condition only. It does not mean "block non-matching prefixes" by itself. A rule with `client_random_prefix = ...` triggers its `action` only when the prefix matches (and the field is available to evaluate). Non-matches (or `None`) simply do not match that rule and continue to fall through. The vulnerability is fixed in version 0.9.115.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
SSVC
Exploitation: poc Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-01-29 21:34 UTC
CWE
  • CWE-284 - Improper Access Control
Assigner
GitHub_M CNA
References
Impacted products
Vendor Product Version
TrustTunnel TrustTunnel Affected: < 0.9.115
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