CVE-2026-5545

Publication date 29 April 2026

Last updated 14 May 2026

Ubuntu priority

Cvss 3 Severity Score

Description

libcurl might in some circumstances reuse the wrong connection when asked to do an authenticated HTTP(S) request after a Negotiate-authenticated one, when both use the same host.

Read the notes from the security team

Mitigation

Avoid using HTTP Negotiate in your application

Status

Show unmaintained releases

Package	Ubuntu Release	Status
curl	26.04 LTS resolute	Fixed 8.18.0-1ubuntu2.1
	25.10 questing	Fixed 8.14.1-2ubuntu1.3
	24.04 LTS noble	Fixed 8.5.0-2ubuntu10.9
	22.04 LTS jammy	Fixed 7.81.0-1ubuntu1.24
	20.04 LTS focal	Vulnerable
	18.04 LTS bionic	Vulnerable
	16.04 LTS xenial	Vulnerable
	14.04 LTS trusty	Vulnerable

Notes

ebarretto

Introduced-in: https://github.com/curl/curl/commit/e56ae1426c

Patch details

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

Package	Patch details
curl	Upstream: 33e4398

Severity score breakdown

Parameter	Value
Base score	6.5 · Medium
Attack vector	Network
Attack complexity	High
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	Low
Integrity impact	High
Availability impact	None
Vector	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N

References

Related Ubuntu Security Notices (USN)

USN-8227-1
curl vulnerabilities
4 May 2026