Vulnerability CVE-2026-115881
Published Sources: pwn.watch
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
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Priority
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CVSS v3
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EPSS score
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Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 30.00 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- no public PoC known
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- —
- Published
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.
Read in glossary- 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.
Read in glossary- 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.
Read in glossary- 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
Included in the same advisory
| Not rated | CVE-2026-115888 | Vulnerability CVE-2026-115888 | — | — |
| Not rated | CVE-2026-115884 | Vulnerability CVE-2026-115884 | — | — |
| Not rated | CVE-2026-115882 | Vulnerability CVE-2026-115882 | — | — |
| Not rated | CVE-2026-115880 | Vulnerability CVE-2026-115880 | — | — |
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<a href="https://intel.neosec.eu/en/cve/CVE-2026-115881"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-115881.svg?lang=en" alt="CVE-2026-115881 – NEOSEC Intel" height="20"></a>