OpenSSL CMS integrity-check flaw lets attackers tamper with messages
Original title: ZDI-26-790: OpenSSL CMS AuthEnvelopedData Improper Validation of Integrity Check Value Vulnerability
ZDI rates CVE-2026-34182 at CVSS 3.1 and says the attacker must already be able to modify the messages.
ZDI published ZDI-26-790 for improper validation of the integrity check value in OpenSSL CMS AuthEnvelopedData handling. Network-adjacent attackers who can already modify those messages can tamper with them. ZDI assigned CVSS 3.1 and CVE-2026-34182. Affected and fixed versions are not listed.
Unconfirmed: Affected versions and any fix are not stated.
- Exploitation requires prior ability to modify CMS AuthEnvelopedData messages.
- ZDI's CVSS rating is 3.1.
- The assigned identifier is CVE-2026-34182.
- The advisory ID is ZDI-26-790.
Impact: tamper with CMS AuthEnvelopedData messages
| Product | Affected |
|---|---|
| OpenSSL | — |
Vulnerabilities mentioned
All| CVE | Vulnerability | CVSS | EPSS | Signals | Published |
|---|---|---|---|---|---|
| CVE-2026-34182 | Issue Summary: Cryptographic Message Services (CMS) processing fails to perform sufficient input validation on the cipher and tag length fields of… | 9.1 | <1% |
From the original article
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 ZDI has assigned a CVSS rating of 3.
zerodayinitiative.com
A short excerpt; the article and its images belong to the publisher. Summary, key facts and assessment above are AI-written from the article and can be wrong.