CVE-2021-20305

Publication date 5 April 2021

Last updated 18 August 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

8.1 · High

Score breakdown

Description

A flaw was found in Nettle in versions before 3.7.2, where several Nettle signature verification functions (GOST DSA, EDDSA & ECDSA) result in the Elliptic Curve Cryptography point (ECC) multiply function being called with out-of-range scalers, possibly resulting in incorrect results. This flaw allows an attacker to force an invalid signature, causing an assertion failure or possible validation. The highest threat to this vulnerability is to confidentiality, integrity, as well as system availability.

Status

Package Ubuntu Release Status
nettle 25.10 questing
Fixed 3.7-2.1ubuntu1
25.04 plucky
Fixed 3.7-2.1ubuntu1
24.10 oracular
Fixed 3.7-2.1ubuntu1
24.04 LTS noble
Fixed 3.7-2.1ubuntu1
23.10 mantic
Fixed 3.7-2.1ubuntu1
23.04 lunar
Fixed 3.7-2.1ubuntu1
22.10 kinetic
Fixed 3.7-2.1ubuntu1
22.04 LTS jammy
Fixed 3.7-2.1ubuntu1
21.10 impish
Fixed 3.7-2.1ubuntu1
21.04 hirsute
Fixed 3.7-2.1ubuntu1
20.10 groovy
Fixed 3.6-2ubuntu0.1
20.04 LTS focal
Fixed 3.5.1+really3.5.1-2ubuntu0.1
18.04 LTS bionic
Fixed 3.4-1ubuntu0.1
16.04 LTS xenial
Fixed 3.2-1ubuntu0.16.04.2
14.04 LTS trusty
Vulnerable

Patch details

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

Package Patch details
nettle

Severity score breakdown

Parameter Value
Base score 8.1 · High
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

References

Related Ubuntu Security Notices (USN)

Other references