Description

In RNP version 0.18.0 a refactoring regression causes the symmetric session key used for Public-Key Encrypted Session Key (PKESK) packets to be left uninitialized except for zeroing, resulting in it always being an all-zero byte array. Any data encrypted using public-key encryption in this release can be decrypted trivially by supplying an all-zero session key, fully compromising confidentiality. The vulnerability affects only public key encryption (PKESK packets).  Passphrase-based encryption (SKESK packets) is not affected. Root cause: Vulnerable session key buffer used in PKESK packet generation. The defect was introduced in commit `7bd9a8dc356aae756b40755be76d36205b6b161a` where initialization logic inside `encrypted_build_skesk()` only randomized the key for the SKESK path and omitted it for the PKESK path.

Weaknesses 1

References 8

• access.redhat.com https://access.redhat.com/security/cve/cve-2025-13402
• aur.archlinux.org https://aur.archlinux.org/packages/rnp
• bugzilla.redhat.com https://bugzilla.redhat.com/show_bug.cgi?id=2415863
• github.com https://github.com/rnpgp/rnp/commit/7bd9a8dc356aae756b40755be76d36205b6b161a
• github.com https://github.com/rnpgp/rnp/releases/tag/v0.18.1
• launchpad.net https://launchpad.net/ubuntu/+source/rnp
• open.ribose.com https://open.ribose.com/advisories/ra-2025-11-20/
• packages.gentoo.org https://packages.gentoo.org/packages/dev-util/librnp

Remediation