CVE-2021-40528

5.9 MEDIUM 1% exploit odds No fix listed

What it is

The ElGamal implementation in Libgcrypt before 1.9.4 allows plaintext recovery because, during interaction between two cryptographic libraries, a certain dangerous combination of the prime defined by the receiver's public key, the generator defined by the receiver's public key, and the sender's ephemeral exponents can lead to a cross-configuration attack against OpenPGP.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of data exposure.
Exploit odds: 1.4% chance of exploitation in the next 30 days (EPSS).
Fix: No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

2021-09-06 19:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 04:07 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 1.4% in the next 30 days (EPSS).
Severity: 5.9 MEDIUM (CVSS).
Fix: none linked yet, which raises it.

Details

Published: 2021-09-06 19:15 UTC
Last modified: 2026-06-17 04:07 UTC
Exploit probability: 1.4% · EPSS, next 30 days
Weakness: CWE-327 · Broken cryptographic algorithm
Record status: Modified

Affected

Gnupg Libgcrypt < 1.9.4

Attack profile CVSS 3.1 · 5.9

Attack vector: Network
Complexity: High
Privileges needed: None
User interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Raw vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-40528.md and follow it. Check whether this project is affected by CVE-2021-40528. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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References

NVD record · CVE.org record