CVE-2026-24882

A flaw in GnuPG before version 2.2.18 allows certificate signature forgery using SHA-1 collision attacks. An attacker can create forged certificate signatures, compromising authentication integrity.

gpgtar in GnuPG before 2.5.19 can allow file overwrite via crafted data in an archive. When extracting an untrusted archive with --directory (-C) into an existing directory containing a pre-existing symlink, gpgtar can follow that symlink and create or overwrite a file outside the selected extraction directory. The write is limited by the extraction user's filesystem permissions.

In GnuPG before version 2.5.17, a crafted CMS (S/MIME) EnvelopedData message with an oversized wrapped session key can cause a stack-based buffer overflow in gpg-agent during PKDECRYPT--kem=CMS handling. This can lead to denial of service, but also memory corruption that could result in remote code execution.

In GnuPG through 2.4.8, if a signed message has \f at the end of a plaintext line, an adversary can construct a modified message that places additional text after the signed material, such that signature verification of the modified message succeeds (although an "invalid armor" message is printed during verification). This is related to use of \f as a marker to denote truncation of a long plaintext line.