Vulnerability CVE-2026-115881

What is affected, what to do

Embedthis GoAhead, the embedded web server behind device-management pages on many IoT, firewall and OT products, fixed eleven advisories in 6.1.1. The critical ones: a Basic and form-auth bypass for users with BF1 (Blowfish) stored hashes where any password works (6.1.0, CVE-2026-115888), OpenSSL builds that load a CRL but never enforce it so revoked mTLS client certificates are still accepted (3.4.5 to 6.1.0, CVE-2026-115881), and Windows CGI command injection through .bat/.cmd scripts run via cmd.exe.

The available sources name no fixed version. Check the vendor guidance in the references below.

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Metrics

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2

NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

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High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.

CRA

The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

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From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.

ISO/IEC 27001

ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

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Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

Embedthis GoAhead, the embedded web server behind device-management pages on many IoT, firewall and OT products, fixed eleven advisories in 6.1.1. The critical ones: a Basic and form-auth bypass for users with BF1 (Blowfish) stored hashes where any password works (6.1.0, CVE-2026-115888), OpenSSL builds that load a CRL but never enforce it so revoked mTLS client certificates are still accepted (3.4.5 to 6.1.0, CVE-2026-115881), and Windows CGI command injection through .bat/.cmd scripts run via cmd.exe. Others include mTLS chain-depth bypass on LibreSSL legacy-verifier builds (CVE-2026-115884), httpoxy-style CGI HTTP_PROXY injection (CVE-2026-115882), CGI ISINDEX option injection (CVE-2026-115880), a 1-byte DH modulus on Mbed TLS builds that makes TLS 1.2 DHE_RSA sessions decryptable, request smuggling, and session fixation. The advisories went out Oct 12; FoxIO's Oct 26 write-up on the three TLS bugs drew wide attention. Upgrade to 6.1.1; devices only get the fix when their manufacturer ships new firmware.

Source: pwn.watch

References & sources

• pwn.watchpwn.watch: GoAhead embedded web server: 6.1.1 fixes critical auth-bypass, mTLS revocation and Windows CGI flawspwn-watch
• github.comGoAhead v6.1.1 release notespwn-watch
• github.comGHSA-qj3g-66fp-rhhr: Authentication bypass for BF1-hashed users (CVE-2026-115888)pwn-watch
• github.comGHSA-5m75-xq69-c3c5: OpenSSL CRL loaded but not enforced (CVE-2026-115881)pwn-watch
• github.comGHSA-584w-ph2x-4gfq: Windows CGI command injection via .bat / .cmd targetspwn-watch
• github.comGoAhead security advisoriespwn-watch
• foxio.ioChoose Your Backend: Three TLS Bugs in GoAheadpwn-watch
• blazeinfosec.comSixteen fixes we found too late to report: our GoAhead investigationpwn-watch
• thehackernews.comGoAhead TLS Flaws Allow Revoked Client Certificates and Enable Session Decryptionpwn-watch
• securityweek.comTLS Flaws Found in GoAhead Web Server Used in Hundreds of Millions of Devicespwn-watch