CVE-2026-6276

stale custom cookie host causes cookie leak

State: Published
Severity: 7.5 High
Published: May 13, 2026
Updated: Sep 15, 2026
Reserved: Apr 14, 2026

Description

Using libcurl, when a custom `Host:` header is first set for an 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.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	CISA-ADP

Weaknesses

CWE-346 Origin Validation Error

Affected Products

Product	Versions
curlcurl	7.71.0 to before 8.14.2Affected 8.15.0 to before 8.16.1Affected 8.17.0 to before 8.20.0Affected
curlcurl	e15e51384a423be31318b3c9c7d612a1aae661fd to before 3a19987a87f393d9394fe5acc7643f6c263c92dbAffected
curlcurl	8.19.0Affected 8.18.0Affected 8.17.0Affected 8.16.0Affected 8.15.0Affected 8.14.1Affected 8.14.0Affected 8.13.0Affected 8.12.1Affected 8.12.0Affected 8.11.1Affected 8.11.0Affected 8.10.1Affected 8.10.0Affected 8.9.1Affected 8.9.0Affected 8.8.0Affected 8.7.1Affected 8.7.0Affected 8.6.0Affected 8.5.0Affected 8.4.0Affected 8.3.0Affected 8.2.1Affected 8.2.0Affected and 28 more versions

References

Every record here comes from the CVE Program’s CVE List. © 1999–2026 The MITRE Corporation. CVE is a registered trademark of The MITRE Corporation. The records are reproduced under the CVE Program terms of use.