How do I check whether I am affected by TECH-202610-goahead-embedded-web-server-tls-bugs-accept-revoked-client-c?

Find devices and firmware that ship GoAhead older than 6.1.1 (Server header or banner, firmware SBOM). Then check the build: OpenSSL backend with mTLS and ME_GOAHEAD_SSL_REVOKE set; Mbed TLS backend offering TLS 1.2 DHE_RSA suites (look for DHE_RSA suites such as 0x009F in JA4S logs, e.g. t120100_009f_1ca028f07214, or a ServerKeyExchange with a 1-byte DH prime 0xFF); LibreSSL 3.2.x/3.3.2-3.3.6 with VERIFY_PEER=1 and VERIFY_ISSUER=0.

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high⚡ Early warning · no CVE yetInfrastructure

GoAhead embedded web server TLS bugs accept revoked client certificates and make some TLS 1.2 sessions decryptable

Q: What is the fix for TECH-202610-goahead-embedded-web-server-tls-bugs-accept-revoked-client-c?

If you build GoAhead into a product, upgrade to 6.1.1 or later. If you run devices, ask the vendor for firmware with GoAhead 6.1.1 and apply it. Until then: turn off finite-field DHE suites (use ECDHE or TLS 1.3); for LibreSSL builds set VERIFY_ISSUER=1 with a trusted CA bundle or move to OpenSSL or LibreSSL 4.x; do not rely on CRL revocation for GoAhead mTLS (rotate the CA or remove the revoked identities another way); and keep device-management interfaces off untrusted networks.

FoxIO disclosed three TLS bugs in Embedthis GoAhead, the embedded web server behind device-management pages in routers, firewalls, printers, and OT/IoT gear (they name Palo Alto Networks, Comcast, D-Link, HP, Canon, Honeywell, GE, Oracle, Siemens, Rockwell, and Digi). (1) OpenSSL-compatible backend, GoAhead 3.4.5-6.1.0: a configured CRL is loaded but never enforced, so revoked mTLS client certificates are still accepted (CVSS 9.1, GOAHEAD-SA-2026-0006). (2) LibreSSL legacy verifier (3.2.x, 3.3.2-3.3.6) with VERIFY_PEER=1 and VERIFY_ISSUER=0, GoAhead <=6.1.0: the chain-depth limit is not enforced (CVSS 7.4, GOAHEAD-SA-2026-0004). (3) Mbed TLS backend, GoAhead 4.0.2-6.1.0: a length typo cuts the 2048-bit DH prime to one byte, so a passive observer can decrypt TLS 1.2 DHE_RSA sessions when the client accepts the parameters (CVSS 5.9, GOAHEAD-SA-2026-0005). Only certain builds and configurations are affected. The bugs were disclosed 2026-10-26 with a fix in GoAhead 6.1.1. No CVE IDs yet and no exploitation reported. Devices only get the fix through vendor firmware updates.

Summary written from the sources below. Check the originals before acting.

Known so far

4/6

high

no CVSS yet; severity from the sources

known so far4 of 6

missing: primary source, exploitation

First public: Oct 26, 2026 UTC
Last modified: Oct 27, 2026
Status: open
Known exploitation: None reported
Public exploit: None on GitHub
EPSS: not scored

First seen by InfraStack 2026-10-27 05:52 UTC. All times on this page are UTC.

Who is affected

1 product

Product	Ecosystem	Affected	Fixed in
GoAhead	–	>=3.4.5 <=6.1.0	6.1.1

Who cares: early-warning, technique
Not affected if: –

How to check

Find devices and firmware that ship GoAhead older than 6.1.1 (Server header or banner, firmware SBOM)
Then check the build: OpenSSL backend with mTLS and ME_GOAHEAD_SSL_REVOKE set; Mbed TLS backend offering TLS 1.2 DHE_RSA suites (look for DHE_RSA suites such as 0x009F in JA4S logs, e.g. t120100_009f_1ca028f07214, or a ServerKeyExchange with a 1-byte DH prime 0xFF); LibreSSL 3.2.x/3.3.2-3.3.6 with VERIFY_PEER=1 and VERIFY_ISSUER=0

The fix

If you build GoAhead into a product, upgrade to 6.1.1 or later
If you run devices, ask the vendor for firmware with GoAhead and apply it

Know the next one before it finds you.

Add to Slack

GoAhead embedded web server TLS bugs accept revoked client certificates and make some TLS 1.2 sessions decryptable

Summary written from the sources below. Check the originals before acting.

Product

Ecosystem

Affected

Fixed in

GoAhead

–

>=3.4.5 <=6.1.0

6.1.1

GoAhead embedded web server TLS bugs accept revoked client certificates and make some TLS 1.2 sessions decryptable

Who is affected

How to check

The fix

Know the next one before it finds you.

GoAhead embedded web server TLS bugs accept revoked client certificates and make some TLS 1.2 sessions decryptable

Who is affected

How to check

The fix

Know the next one before it finds you.

Who had it, and when

Sources