OpenSSL CMS AuthEnvelopedData Improper Validation of Integrity Check Value Vulnerability

October 22nd, 2026
ZDI-26-790 ZDI-CAN-30385

CVE ID

CVE-2026-34182

CVSS Score

3.1 AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected Vendors

OpenSSL

Affected Products

OpenSSL

Vulnerability Details

This vulnerability allows network-adjacent attackers to tamper with CMS AuthEnvelopedData messages on affected installations of OpenSSL. An attacker must first obtain the ability to modify CMS AuthEnvelopedData messages in order to exploit this vulnerability.

The specific flaw exists within the handling of AES-GCM message authentication codes. The issue results from an improper integrity check. An attacker can leverage this vulnerability to tamper with authenticated data.

Additional Details

OpenSSL has issued an update to correct this vulnerability. More details can be found at:
https://openssl-library.org/news/secadv/20260609.txt

Disclosure Timeline

  • 2026-04-09 - Vulnerability reported to vendor
  • 2026-10-22 - Coordinated public release of advisory
  • 2026-10-22 - Advisory Updated

Credit

TrendAI Zero Day Initiative

Back to Advisories