---
title: "CVE-2026-117666: ssl_verify_fun - Improper Validation of Certificate with Host Mismatch"
description: "ssl_verify_fun 1.0.1 before 1.1.8 contains an improper validation of certificate with host mismatch caused by partial-label wildcard matching in try_match_wildcard/4 in src/ssl_verify_hostname.erl, letting man-in-the-middle attackers impersonate TLS peers via certificates with wildcards consuming dots, exploit requires usage of vulnerable ssl_verify_fun with disabled SNI or direct calls to verify_cert_hostname/2."
url: https://panop.io/threat-heartbeat/CVE-2026-117666/
---

# CVE-2026-117666 ssl\_verify\_fun - Improper Validation of Certificate with Host Mismatch

ssl\_verify\_fun 1.0.1 before 1.1.8 contains an improper validation of certificate with host mismatch caused by partial-label wildcard matching in try\_match\_wildcard/4 in src/ssl\_verify\_hostname.erl, letting man-in-the-middle attackers impersonate TLS peers via certificates with wildcards consuming dots, exploit requires usage of vulnerable ssl\_verify\_fun with disabled SNI or direct calls to verify\_cert\_hostname/2.

CVSS base score 9.1 /10

Critical

CISA KEV

Not listed

Public exploit

None known

EPSS

0.19% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-117666)

## Details

Type

Improper Validation of Certificate with Host Mismatch

Impact

Man In The Middle

CVSS vector

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Published

30 October 2026

Updated

1 November 2026

Weakness

[CWE-297](https://cwe.mitre.org/data/definitions/297.html)

## Vendor fix

Update ssl\_verify\_fun to version 1.1.8 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-117666](https://nvd.nist.gov/vuln/detail/CVE-2026-117666)
- [https://github.com/deadtrickster/ssl\_verify\_fun.erl/pull/33](https://github.com/deadtrickster/ssl_verify_fun.erl/pull/33)
- [https://github.com/deadtrickster/ssl\_verify\_fun.erl/security/advisories/GHSA-7gw2-hphm-c5px](https://github.com/deadtrickster/ssl_verify_fun.erl/security/advisories/GHSA-7gw2-hphm-c5px)
- [https://osv.dev/vulnerability/EEF-CVE-2026-117666](https://osv.dev/vulnerability/EEF-CVE-2026-117666)
- [https://cna.erlef.org/cves/CVE-2026-117666.html](https://cna.erlef.org/cves/CVE-2026-117666.html)
- [https://github.com/deadtrickster/ssl\_verify\_fun.erl/commit/a49ca56923356c7a3981692b23c42ef32c2990e0](https://github.com/deadtrickster/ssl_verify_fun.erl/commit/a49ca56923356c7a3981692b23c42ef32c2990e0)
- [https://github.com/deadtrickster/ssl\_verify\_fun.erl/commit/ca34031299cd2e0c98794c0da4ba556b94e39aad](https://github.com/deadtrickster/ssl_verify_fun.erl/commit/ca34031299cd2e0c98794c0da4ba556b94e39aad)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

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