Vulnerability Report

CVE-2026-6276

Title: Stale Host header cookie leakage in libcurl

Information Disclosure

Proof Of Concept

No public PoC currently indexed for CVE-2026-6276.

CWE Category NVD-CWE-noinfo
Published Date May 13, 2026
Modified Date May 14, 2026
Exploit Status Not Found
Score 7.5 CVSS v
Exploit Probability (EPSS)
0.01%

Vulnerability Summary

CVE-2026-6276: 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.

Impacted Vendors

H
haxx 1
D
daniel_stenberg 1

Reference Links

https://curl.se/docs/CVE-2026-6276.html https://curl.se/docs/CVE-2026-6276.json https://hackerone.com/reports/3671818 http://www.openwall.com/lists/oss-security/2026/04/29/13
CVSS v3.1
Source Entity 134c704f-9b21-4f2e-91b3-4a467353bcc0
Severity HIGH
7.5
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v3.1
Source Entity [email protected]
Severity HIGH
7.5
Attack Vector
NETWORK
Complexity
LOW
Privileges
N/A
Interaction
NONE
Confidentiality
N/A
Integrity
N/A
Availability
N/A
Scope
UNCHANGED
RAW VECTOR CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Associated Attack Patterns (CAPEC)

Total: Patterns

CVE-2026-6276 Exploits & PoCs (Proof Of Concept)

No public PoCs found in our database for this CVE.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

MODIFIED

Vulnerability data updated via NVD.

Attack Vector Matrix

Access Vector NETWORK
Complexity LOW
Privileges N/A
Interaction NONE
CVSS Vector String CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Stack

No specific products linked.