GoAhead is a small web server that device makers compile into firmware for router, printer, gateway and industrial-controller admin pages. FoxIO's Sébastien Féry published three TLS bugs on Oct 26, all fixed in GoAhead 6.1.1 (given to device makers Aug 2, advisories public Oct 12).

• OpenSSL backend, CVE-2026-115881 (vendor CVSS 9.1): versions 3.4.5 to 6.1.0 load a configured certificate revocation list but never switch revocation checking on, so a revoked client certificate (for example from a stolen or retired device) still passes mutual-TLS login. Only builds with mTLS, a CA bundle, issuer checking and a CRL configured are affected; the default build has no mTLS.
• LibreSSL legacy verifier (3.2.x, 3.3.2-3.3.6), CVE-2026-115884 (7.4): an over-long client chain is accepted when client certificates are required but issuer checking is off.
• Mbed TLS backend (5.9, no CVE): a length typo sends a 1-byte Diffie-Hellman value, so TLS 1.2 DHE_RSA sessions with clients that accept it can be decrypted by anyone who recorded them. Mainstream browsers, OpenSSL, Go and Java refuse it.

The same release closes 11 advisories in total, including a login bypass for accounts whose password is stored in the newer Blowfish format. Which backend and settings a device uses is fixed at compile time, so owners can't tell from outside. What to do: ask vendors of devices with GoAhead-based admin pages whether they ship 6.1.1, keep those admin pages off the internet, and after updating end sessions and change Blowfish-stored passwords as EmbedThis advises. The CVE IDs were not yet live in the public CVE/NVD databases as of Oct 27.