CVE-2026-86414

Publication date 14 October 2026

Last updated 3 November 2026

Ubuntu priority

Cvss 3 Severity Score

Description

An HTTP proxy can trick libcurl into sending the origin's credentials (Basic password, or a Negotiate/Kerberos ticket) to the proxy itself, by answering the `CONNECT` tunnel request with 401 `WWW-Authenticate:` instead of the expected 407 `Proxy-Authenticate:`.

Why is this CVE low priority?

Upstream defined this as low severity

Learn more about Ubuntu priority

Status

Show unmaintained releases

Package	Ubuntu Release	Status
curl	26.10 stonking	Fixed in 8.20.0-2ubuntu11.1
	26.04 LTS resolute	Fixed in 8.18.0-1ubuntu2.8
	24.04 LTS noble	Fixed in 8.5.0-2ubuntu10.16
	22.04 LTS jammy	Fixed in 7.81.0-1ubuntu1.30
	20.04 LTS focal	Fixed in 7.68.0-1ubuntu2.25+esm10
	18.04 LTS bionic	Fixed in 7.58.0-2ubuntu3.24+esm15
	16.04 LTS xenial	Fixed in 7.47.0-1ubuntu2.19+esm21
	14.04 LTS trusty	Fixed in 7.35.0-1ubuntu2.20+esm24

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Patch details

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

Package	Patch details
curl	Upstream: 2956af6

Severity score breakdown

CVSS version: CVSS v3.0

Base score 9.1 · Critical

Base metrics

Parameter	Value
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality impact	High
Integrity impact	High
Availability impact	None

Scores

Parameter	Value
Base score	9.1 · Critical
Exploitability score	-
Impact score	-

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

References

Related Ubuntu Security Notices (USN)

USN-8927-1
curl vulnerabilities
14 October 2026

USN-8932-1
curl vulnerabilities
14 October 2026

USN-8927-2
curl vulnerabilities
19 October 2026