Improper validation of certificate with host mismatch in otp - CVE-2026-42790
Published: July 2, 2026
Vulnerability identifier: #VU136813
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-42790
CWE-ID: CWE-297
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: erlang
Affected software:
otp
otp
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass certificate hostname validation.
The vulnerability exists due to improper validation of certificate with host mismatch in public_key:pkix_verify_hostname/3 when processing TLS certificates that lack a Subject Alternative Name extension or contain no domain name in that extension. A remote attacker can present a specially crafted certificate during a man-in-the-middle position to bypass certificate hostname validation.
Exploitation requires the ability to intercept network traffic and, in the worst case, control a DNS-constrained sub-CA key.
How to mitigate CVE-2026-42790
Install security update from vendor's website.