CVE-2026-24904 - TrustTunnel has `client_random_prefix` rule bypass via fragmented or partial TLS ClientHello

CVE-2026-24904 - TrustTunnel has `client_random_prefix` rule bypass via fragmented or partial TLS ClientHello

https://cvefeed.io/rssfeed/latest.atom / Fri, 01/30/2026 - 01:59
CVE ID : CVE-2026-24904
Published : Jan. 29, 2026, 10:15 p.m. | 1 hour, 18 minutes ago
Description : 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
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