CVE-2026-42784: Sequoia-openpgp: sequoia-openpgp: cryptographic integrity compromise via key flag confusion
A flaw was found in sequoia-openpgp. The library incorrectly infers key flags for older certificates when a key flags subpacket is missing, leading to a discrepancy in how key capabilities are viewed. This key flag confusion allows an attacker to bypass the back-signature check. Consequently, an attacker can illegitimately bind an arbitrary subkey to their own certificate and forge signatures, completely compromising cryptographic integrity.
Affected Software
Event History
Frequently Asked Questions
Which certificates are affected by the key flag confusion?
The issue affects older certificates where the key flags subpacket is missing. The library incorrectly infers capabilities for those certificates, creating a discrepancy in key capability handling.
What does an attacker need to do to exploit this flaw?
An attacker needs to exploit the capability discrepancy to bypass the back-signature check. This allows them to bind an arbitrary subkey to their own certificate and forge signatures.
What is the practical security impact?
Successful exploitation completely compromises cryptographic integrity. Forged signatures may be accepted because an attacker can illegitimately attach a subkey to their certificate.