Read the docs
TI-2026-83395 Aliases CVE-2026-117666

Partial wildcard certificates match wrong hosts in ssl_verify_fun

Priority MEDIUM 40CWE-297Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
High
Attack requirements
Present
Impact type
—
Confidentiality · integrity · availability
High · High · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

The deadtrickster ssl_verify_fun library from 1.0.1 before 1.1.8 accepts partial-label wildcard certificates for hosts they should not match (CWE-297). A certificate for f*.example.net is accepted for f.evil.example.net because the wildcard also consumes dots. An adversary in the middle can impersonate a TLS peer with such a certificate, but clients that keep SNI enabled still reject the mismatch, so exposure is limited to clients that disable SNI and servers that verify client certificate hostnames with this library.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

Description from the CNA

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0019 8th percentileScored 2026-11-07
Fix Fixed ssl_verify_fun (deadtrickster): 1.1.8

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
deadtricksterssl_verify_fun1.0.1 to before 1.1.81.1.8Patch availableCNA
  • ssl_verify_fun Vendordeadtrickster Affected 1.0.1 to before 1.1.8 Fixed in 1.1.8 Patch available CNA

CPE names CNA · 1

CPEVersionsRoleVendor
cpe:2.3:a:deadtrickster:ssl_verify_fun:*:*:*:*:*:*:*:*——deadtrickster
  • cpe:2.3:a:deadtrickster:ssl_verify_fun:*:*:*:*:*:*:*:* Versions — — ·deadtrickster

Remediation

Update ssl_verify_fun to version 1.1.8, which fixes the flaw.

Written with Claude Haiku 5.5 from the sources below · 2026-11-06

  • Fix · CNA ssl_verify_fun (deadtrickster) Fixed in 1.1.8

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-30 Threatist record created from CVE-2026-117666
  2. 2026-11-01 Priority changed: MEDIUM → LOW
  3. 2026-11-03 Affected versions changed · Red Hat
  4. 2026-11-03 CVSS score added · Red Hat
  5. 2026-11-06 CISA SSVC decision points changed
  6. 2026-11-06 Priority changed: LOW → MEDIUM

References

Sources