CVE-2021-33560

Name: CVE-2021-33560
Creator: NVD / NIST
Published: 2021-06-08T11:15:07.767+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 2.34%

Last modified Jun 17, 2026

CVE-2021-33560 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. Libgcrypt before 1.8.8 and 1.9.x before 1.9.3 mishandles ElGamal encryption because it lacks exponent blinding to address a side-channel attack against mpi_powm, and the window size is not chosen appropriately. This, for example, affects use of ElGamal in OpenPGP.. EPSS estimates a 2.34% chance of exploitation in the next 30 days.

Description

Libgcrypt before 1.8.8 and 1.9.x before 1.9.3 mishandles ElGamal encryption because it lacks exponent blinding to address a side-channel attack against mpi_powm, and the window size is not chosen appropriately. This, for example, affects use of ElGamal in OpenPGP.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

2.34%

81.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Gnupg	Libgcrypt	< 1.8.8
Gnupg	Libgcrypt	>= 1.9.0, < 1.9.3
Debian	Debian Linux	9.0
Fedoraproject	Fedora	33
Fedoraproject	Fedora	34
Oracle	Communications Cloud Native Core Binding Support Function	1.11.0
Oracle	Communications Cloud Native Core Network Function Cloud Native Environment	1.9.0
Oracle	Communications Cloud Native Core Network Function Cloud Native Environment	1.10.0
Oracle	Communications Cloud Native Core Network Repository Function	1.14.0
Oracle	Communications Cloud Native Core Network Repository Function	1.15.0
Oracle	Communications Cloud Native Core Network Repository Function	1.15.1
Oracle	Communications Cloud Native Core Network Slice Selection Function	1.8.0
Oracle	Communications Cloud Native Core Service Communication Proxy	1.15.0

References

https://dev.gnupg.org/T5305Release Notes, Vendor Advisory
https://dev.gnupg.org/T5328Vendor Advisory
https://dev.gnupg.org/T5466Release Notes, Vendor Advisory
https://dev.gnupg.org/rCe8b7f10be275bcedb5fc05ed4837a89bfd605c61Patch, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00021.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BKKTOIGFW2SGN3DO2UHHVZ7MJSYN4AAB/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/R7OAPCUGPF3VLA7QAJUQSL255D4ITVTL/
https://security.gentoo.org/glsa/202210-13Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.htmlThird Party Advisory
https://dev.gnupg.org/T5305Release Notes, Vendor Advisory
https://dev.gnupg.org/T5328Vendor Advisory
https://dev.gnupg.org/T5466Release Notes, Vendor Advisory
https://dev.gnupg.org/rCe8b7f10be275bcedb5fc05ed4837a89bfd605c61Patch, Vendor Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00021.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/BKKTOIGFW2SGN3DO2UHHVZ7MJSYN4AAB/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/R7OAPCUGPF3VLA7QAJUQSL255D4ITVTL/
https://security.gentoo.org/glsa/202210-13Third Party Advisory
https://www.oracle.com/security-alerts/cpuapr2022.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpujan2022.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpujul2022.htmlPatch, Third Party Advisory
https://www.oracle.com/security-alerts/cpuoct2021.htmlThird Party Advisory

Timeline

Published: Jun 8, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-33560?

How severe is CVE-2021-33560?

CVE-2021-33560 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 2.34% probability of exploitation in the next 30 days.

How do I fix CVE-2021-33560?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-33560?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST