Vulnerability in Adguard Trusttunnel
CVE-2026-24904
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.003 (19.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 20th percentile — 19.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000
Affected products
- Adguard Trusttunnel
- Trusttunnel — versions < 0.9.115
Weakness classification (CWE)
References
- github.com/TrustTunnel/TrustTunnel/security/advisories/GHSA-fqh7-r5gf-3r87 (Exploit, Patch, Vendor Advisory)
- github.com/TrustTunnel/TrustTunnel/commit/aa5060145506952b9431b0ed3edb52bb6c08d… (Patch)
Frequently asked questions
- What is CVE-2026-24904?
- CVE-2026-24904 is a medium-severity vulnerability in Adguard Trusttunnel, classified under Improper Access Control. CVSS score: 5.3/10. Published 2026-01-29.
- How severe is CVE-2026-24904?
- Medium severity. CVSS v3 base score is 5.3 out of 10.