Input validation error in OpenSSL - CVE-2026-42770
Published: June 10, 2026
Vulnerability identifier: #VU134285
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2026-42770
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: OpenSSL Software Foundation
Affected software:
OpenSSL
OpenSSL
Detailed vulnerability description
The vulnerability allows a remote attacker to recover the victim's private key.
The vulnerability exists due to improper input validation in EVP_PKEY_derive_set_peer() when validating a DHX (X9.42) peer key using the peer-supplied q parameter for subgroup membership checks. A remote attacker can present a forged DHX peer key to recover the victim's private key.
The realistic attack surface is narrow and is principally limited to deployments using long-lived X9.42 DHX static keys with interactive protocols.
How to mitigate CVE-2026-42770
Install security update from vendor's website.