GoAhead TLS flaws accept revoked certificates and weaken sessions
Original title: GoAhead TLS Flaws Allow Revoked Client Certificates and Enable Session Decryption
GoAhead 6.1.1 fixes three TLS issues; FoxIO published proof-of-concept code, with no attacks reported.
EmbedThis GoAhead loaded a certificate revocation list on its OpenSSL mutual-TLS path but did not enforce it, so a revoked client certificate could still authenticate. Two other build-specific flaws accept an over-long LibreSSL certificate chain and, on Mbed TLS, send a 1-byte Diffie-Hellman value that can let a passive observer decrypt the session. Version 6.1.1, sent to device makers on August 2 and published October 12, fixes them. FoxIO published proof-of-concept code; no source reported attacks as of October 27.
Unconfirmed: CVE identifiers were not yet in NVD, and whether any manufacturer shipped 6.1.1 is unknown.
- CVE-2026-115881 affects OpenSSL builds 3.4.5 through 6.1.0 and is rated 9.1.
- CVE-2026-115884 affects listed older LibreSSL builds through 6.1.0, rated 7.4.
- The Mbed TLS issue, rated 5.9 with no CVE, spans 4.0.2 through 6.1.0.
- Mbed TLS builds are unaffected by the revocation bug.
- A separate 6.1.0 Blowfish login bypass is also closed in 6.1.1.
Impact: Revoked clients authenticate; weak DH can expose sessions
| Product | Affected | Fixed in |
|---|---|---|
| EmbedThis GoAhead (OpenSSL backend) | 3.4.5 through 6.1.0 | 6.1.1 |
| EmbedThis GoAhead (LibreSSL legacy verifier) | 6.1.0 and earlier on LibreSSL 3.2.x and 3.3.2–3.3.6 | 6.1.1 |
| EmbedThis GoAhead (Mbed TLS) | 4.0.2 through 6.1.0 | 6.1.1 |
- 1.Upgrade affected GoAhead builds to 6.1.1 when the device maker ships firmware.
- 2.On the LibreSSL issue, enable issuer checking or use OpenSSL or LibreSSL 4.x.
- 3.After upgrading, end sessions, restart, and change Blowfish-stored passwords.
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2026-115881 | — | — | — | ||
| CVE-2026-115884 | — | — | — |
From the original article
4 min read at thehackernews.com
The GoAhead embedded web server loaded a certificate revocation list into its default TLS backend but never turned revocation checking on, so a revoked client certificate could still pass login on affected setups. The flaw is in builds that use the OpenSSL backend with mutual-TLS, where the server checks a client certificate and vice versa, and a revocation list is configured to block revoked
thehackernews.com
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