CVE-2025-47934: 
JavaScript vulnerability analysis and mitigation

OpenPGP.js, a JavaScript implementation of the OpenPGP protocol, contains a critical vulnerability (CVE-2025-47934) discovered in May 2025 by Edoardo Geraci and Thomas Rinsma of Codean Labs. The vulnerability affects versions 5.0.1 through 5.11.2 and 6.0.0-alpha.0 through 6.1.0, allowing attackers to spoof message signature verifications in both the openpgp.verify and openpgp.decrypt functions (GitHub Advisory).

The vulnerability stems from improper verification of cryptographic signatures, where a maliciously modified message can cause the functions to return a valid signature verification result while returning data that was not actually signed. This affects both inline (non-detached) signed messages using openpgp.verify and signed-and-encrypted messages using openpgp.decrypt with verificationKeys. Notably, detached signature verifications are not affected by this vulnerability. The issue has been assigned a CVSS 4.0 Base Score of 8.7 (HIGH) with the vector string CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N (NVD).

An attacker who obtains a single valid message signature (inline or detached) and the corresponding plaintext data can construct an inline-signed message or signed-and-encrypted message containing arbitrary data of their choice. This modified message will appear as legitimately signed by affected versions of OpenPGP.js, effectively allowing signature verification to be spoofed (GitHub Advisory).

The vulnerability has been patched in versions 5.11.3 and 6.1.1. For users unable to update immediately, two workarounds are available: For inline-signed messages, extract the message and signature(s) from openpgp.readMessage output and verify each signature as a detached signature. For signed+encrypted messages, decrypt and verify in two steps by first calling openpgp.decrypt without verificationKeys, then verify the signature(s) separately (GitHub Advisory).

The vulnerability was discovered through the OpenPGP.js bug bounty program hosted by YesWeHack and sponsored by the Sovereign Tech Agency. The most notable user of OpenPGP is encrypted email provider Proton Mail, which maintains the library and uses the technology to offer end-to-end encryption for its more than 100 million registered accounts (Wiz).