Signed-message forgery via form-feed hash truncation
Published Dec 27, 2025 · Updated Dec 27, 2025
Improper signature verification in GNU Project GnuPG 2.4.8 and earlier allows attackers to append unsigned text to clear-signed messages. Cleartext hashing treats a form feed as the marker inserted for a truncated line, so distinct attacker-controlled suffixes produce the same signed hash input. Exploitation requires an existing signature and plaintext containing a form-feed line ending; verification reports invalid armor but still reports a good signature.
Summary
What happened
Improper signature verification in GNU Project GnuPG 2.4.8 and earlier allows attackers to append unsigned text to clear-signed messages. Cleartext hashing treats a form feed as the marker inserted for a truncated line, so distinct attacker-controlled suffixes produce the same signed hash input. Exploitation requires an existing signature and plaintext containing a form-feed line ending; verification reports invalid armor but still reports a good signature.
The record
- CVE
- CVE-2025-68972
- Published
- Dec 27, 2025
- Updated
- Dec 27, 2025
- Vendor
- The GnuPG Project
- Product
- GnuPG
- Classifications
- CWE-347, T1565.002
- Attack vector
- local
- Privileges
- unauthenticated
Timeline
How it unfolded
- Dec 27, 2025CVE publishedPublication date reported by the CVE source.
- Dec 27, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <=2.4.8
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- gpg.fail form-feed reproductionproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
Check the software in your environment
Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.
Book a demo