CVE-2026-6276

Publication date 29 April 2026

Last updated 14 May 2026

Ubuntu priority

Cvss 3 Severity Score

Description

Using libcurl, when a custom `Host:` header is first set for a HTTP request and a second request is subsequently done using the same *easy handle* but without the custom `Host:` header set, the second request would use stale information and pass on cookies meant for the first host in the second request. Leak them.

Read the notes from the security team

Why is this CVE low priority?

Upstream defined this as low severity.

Learn more about Ubuntu priority

Mitigation

Avoid using custom `Host:` headers.

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	Not affected
	18.04 LTS bionic	Not affected
	16.04 LTS xenial	Not affected
	14.04 LTS trusty	Not affected

Notes

ebarretto

Introduced-in: https://github.com/curl/curl/commit/e15e51384a423be3131

Patch details

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

Package	Patch details
curl	Upstream: 3a19987

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	None
Integrity impact	None
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Related Ubuntu Security Notices (USN)

USN-8227-1
curl vulnerabilities
4 May 2026