CVE-2021-20305

Publication date 5 April 2021

Last updated 24 July 2024

Ubuntu priority

Cvss 3 Severity Score

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

Show unmaintained releases

Package	Ubuntu Release	Status
nettle	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	Upstream: a638937 Upstream: 971bed6 Upstream: 74ee0e8 Upstream: 51f643e Upstream: 401c8d5 Upstream: ae3801a Upstream: 63f222c

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)

USN-4906-1
Nettle vulnerability
13 April 2021