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01 Record

CVE-2021-40528

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

MediumPUBLISHEDCNA: mitre
CNA base score5.9 CVSS v3.xCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
View raw JSON

02 Description

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

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
1.42% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 72.6% of scored records. A rank, not a probability.
NVD base score
5.9 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD analysis status
Modified. NVD last modified this record on 2026-06-17.
Red Hat severity
Moderate. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2021-09-06 00:00Z5 YR AGO
Last updated
2025-06-09 15:13Z1 YR AGO
Reserved
2021-09-06
Assigning CNA
mitre
Record state
PUBLISHED
Severity
Medium (CVSS 5.9)
CNA CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
Weaknesses
  • CWE-327Use of a Broken or Risky Cryptographic AlgorithmClass
Data version
5.1
Document digest
9a055a9b0a8401a7d7ed90caa2d421e4e1842ab6ebcd0c4cab9690272a521842

05 Affected products

VendorProductVersionsPlatforms
gnupglibgcryptNot specified—
redhatenterprise_linuxNot specified—

06 References

07 Fixed in

AlmaLinux 8

  • libgcrypt
    Fixed in 1.8.5-7.el8_6
  • libgcrypt-devel
    Fixed in 1.8.5-7.el8_6

Source: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

CloudLinux 8

  • libgcrypt
    Fixed in 1.8.5-7.el8_6
  • libgcrypt-devel
    Fixed in 1.8.5-7.el8_6

Derived from AlmaLinux 8. Partial coverage: only packages taken from AlmaLinux 8 are listed.

Source: CloudLinux errata, CloudLinux Inc. Derived from: AlmaLinux, AlmaLinux OS. Copyright (c) 2023 AlmaLinux OS. Licensed under MIT License. Received through OSV.dev. Reformatted by exploit.cc.

Debian 12

  • libgcrypt20
    Fixed in 1.8.7-6

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • libgcrypt20
    Fixed in 1.8.7-6

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • libgcrypt20
    Fixed in 1.8.7-6

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 18.04 LTS

  • libgcrypt20
    Fixed in 1.8.1-4ubuntu1.3

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 20.04 LTS

  • libgcrypt20
    Fixed in 1.8.5-5ubuntu1.1

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 22.04 LTS

  • libgcrypt20
    Fixed in 1.8.7-5ubuntu2

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 16.04 LTS

  • libgcrypt20
    Fixed in 1.6.5-2ubuntu0.6+esm1
    Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro FIPS-updates 18.04 LTS

  • libgcrypt20
    Fixed in 1.8.1-4ubuntu1.fips.3
    Available with Ubuntu Pro: https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro FIPS-updates 20.04 LTS

  • libgcrypt20
    Fixed in 1.8.5-5ubuntu1.fips.1.1
    Available with Ubuntu Pro: https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro FIPS 18.04 LTS

  • libgcrypt20
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro FIPS 20.04 LTS

  • libgcrypt20
    Fixed in 1.8.5-5ubuntu1.fips.1.1
    Available with Ubuntu Pro: https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.