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CVE-2021-33560

Publication date 8 June 2021

Last updated 24 July 2024

Ubuntu priority

Low

Why this priority?

Cvss 3 Severity Score

7.5 · High

Score breakdown

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.

Read the notes from the security team

Status

Package Ubuntu Release Status
libgcrypt20 24.10 oracular
Fixed 1.8.7-5ubuntu2
24.04 LTS noble
Fixed 1.8.7-5ubuntu2
23.10 mantic
Fixed 1.8.7-5ubuntu2
23.04 lunar
Fixed 1.8.7-5ubuntu2
22.10 kinetic
Fixed 1.8.7-5ubuntu2
22.04 LTS jammy
Fixed 1.8.7-5ubuntu2
21.10 impish
Fixed 1.8.7-5ubuntu2
21.04 hirsute
Fixed 1.8.7-2ubuntu2.1
20.10 groovy Ignored end of life
20.04 LTS focal
Fixed 1.8.5-5ubuntu1.1
18.04 LTS bionic
Fixed 1.8.1-4ubuntu1.3
16.04 LTS xenial
14.04 LTS trusty Not in release

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Notes

mdeslaur

This CVE was originally for the issue that is now CVE=2021-40528 but somehow got switched to the exponent blinding issue instead. The fix to add exponent blinding appears to only have been added to 1.9.x but never backported to 1.8.x, contrary to the CVE description The commit below was never backported to 1.8.x because the upstream developers consider this hardening and not a security issue.

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
libgcrypt20

Severity score breakdown

Parameter Value
Base score 7.5 · High
Attack vector Network
Attack complexity Low
Privileges required None
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact None
Availability impact None
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

References

Related Ubuntu Security Notices (USN)

    • USN-5080-1
    • Libgcrypt vulnerabilities
    • 16 September 2021
    • USN-5080-2
    • Libgcrypt vulnerabilities
    • 16 September 2021

Other references