CVE-2026-42771: openssl Out-of-bounds Read

Vulnerability summary

CVE-2026-42771 is a medium (CVSS 6.2) Out-of-bounds Read vulnerability in openssl. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 4.8% of scored vulnerabilities.

Timeline

1. 09-06-2026
   PublishedVulnerability first disclosed.
2. 10-06-2026
   Last modifiedVulnerability information updated.

Description

Issue summary: When the X509_VERIFY_PARAM_set1_email is called by an application to validate a crafted e-mail address, such as during S/MIME message validation, an out of bounds read can happen. Impact summary: This out of bounds read will not directly exfiltrate the data read to the attacker so the most likely result is a crash and a Denial of Service. An internal helper function called from X509_VERIFY_PARAM_[set|add]_email() used a wrong length when validating the local part of an email address. This could cause the 64 octet limit on the local part of an email address to be not enforced, or cause an out of bound read and potentially a crash. The bug is reachable via S-MIME validation with a crafted From: address supplied in an email message that can potentially cause a crash. No FIPS modules are affected by this issue as the affected code is outside the OpenSSL FIPS module boundary.

• CWE-125Out-of-bounds ReadThe product reads data past the end, or before the beginning, of the intended buffer.