Vulnerability Report

CVE-2026-11856

Title: libcurl Digest authentication header leakage to different origin

Other

Proof Of Concept

No public PoC currently indexed for CVE-2026-11856.

CWE Category NVD-CWE-noinfo

Published Date Jul 03, 2026

Modified Date Jul 07, 2026

Exploit Status Not Found

Score 9.8 CVSS v

Exploit Probability (EPSS)

1.06%

Vulnerability Summary

CVE-2026-11856: Successfully using libcurl to do a transfer to a specific HTTP origin (`hostA`) with **Digest** authentication and then changing the origin to a different one (`hostB`) for a second transfer, reusing the same handle, makes libcurl wrongly pass on the `Authorization:` header field meant for `hostA`, to `hostB`.

Impacted Vendors

haxx 1

Reference Links

https://curl.se/docs/CVE-2026-11856.html https://curl.se/docs/CVE-2026-11856.json https://hackerone.com/reports/3793260

CVSS v3.1

Source Entity 134c704f-9b21-4f2e-91b3-4a467353bcc0

Severity CRITICAL

9.8

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:H/I:H/A:H

Associated Attack Patterns (CAPEC)

Total: Patterns