Signature spoofing attack in GnuPG

1) Improper Verification of Cryptographic Signature

EUVDB-ID: #VU64909

Risk: Medium

CVSSv4.0: 4.6 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2022-34903

CWE-ID: CWE-347 - Improper Verification of Cryptographic Signature

Exploit availability: No

Description

The vulnerability allows a remote attacker to perform spoofing attack.

The vulnerability exists due to an error in GnuPG, which allows signature spoofing via arbitrary injection into the status line. A remote attacker who controls the secret part of any signing-capable key or subkey in the victim's keyring, can take advantage of this flaw to provide a correctly-formed signature that some software, including gpgme, will accept to have validity and signer fingerprint chosen from the attacker.

Mitigation

Install update from vendor's website.

Vulnerable software versions

GnuPG: 2.2 - 2.3.6

CPE2.3

• cpe:2.3:a:gnu:gnupg:2.2:*:*:*:*:*:*:*
• cpe:2.3:a:gnu:gnupg:2.2.0:*:*:*:*:*:*:*
• cpe:2.3:a:gnu:gnupg:2.2.1:*:*:*:*:*:*:*

External links

https://dev.gnupg.org/T6027
https://bugs.debian.org/1014157
https://www.openwall.com/lists/oss-security/2022/06/30/1
https://www.openwall.com/lists/oss-security/2022/07/02/1
https://www.debian.org/security/2022/dsa-5174

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.