CVE-2026-117666
Received
Received - Intake
Hostname Validation Bypass in ssl_verify_fun
Vulnerability report for CVE-2026-117666, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.
Publication date: 2026-10-30
Last updated on: 2026-10-30
Assigner: EEF
Description
Description
Improper Validation of Certificate with Host Mismatch vulnerability in deadtrickster ssl_verify_fun allows an adversary in the middle to impersonate a TLS peer via a certificate that carries a partial-label wildcard. try_match_wildcard/4 in src/ssl_verify_hostname.erl anchors only the text before and after the * of an identifier such as f*.example.net, so the wildcard also consumes dots and the certificate is accepted for f.evil.example.net. RFC 6125 confines a wildcard to the left-most label. The same matcher lets *.168.1.1 match the IP literal 192.168.1.1. Whole-label wildcards are matched correctly.
Erlang/OTP 20.0 and later check the hostname in ssl before a user verify_fun sees valid_peer, so a client that keeps server_name_indication set rejects the mismatch regardless. Exposed are clients that disable SNI, servers that verify client certificate hostnames with this library, and direct callers of verify_cert_hostname/2.
This issue affects ssl_verify_fun: from 1.0.1 before 1.1.8.
CVSS Scores
EPSS Scores
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| deadtrickster | ssl_verify_fun | 1.0.1 |
| deadtrickster | ssl_verify_fun | a49ca56923356c7a3981692b23c42ef32c2990e0 |
Helpful Resources
Exploitability
CWE
KEV
| CWE ID | Description |
|---|---|
| CWE-297 | The product communicates with a host that provides a certificate, but the product does not properly ensure that the certificate is actually associated with that host. |
