CVE-2026-11856

cross-origin Digest auth state leak

Published Jul 3, 2026 CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed
Description
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`.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8651-1 curl vulnerability
History
Type Values Removed Values Added
Description 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`. 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`.
Type Values Removed Values Added
Weaknesses CWE-200
Type Values Removed Values Added
First Time appeared Redhat
Redhat hummingbird
Weaknesses CWE-201
CPEs cpe:/a:redhat:hummingbird:1
Vendors & Products Redhat
Redhat hummingbird
References
Metrics threat_severity

None

threat_severity

Moderate

Type Values Removed Values Added
Weaknesses CWE-200
Type Values Removed Values Added
Weaknesses CWE-200
Type Values Removed Values Added
Weaknesses CWE-200
Metrics cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Weaknesses CWE-200
Type Values Removed Values Added
Weaknesses CWE-200
Type Values Removed Values Added
Weaknesses CWE-798
Type Values Removed Values Added
Weaknesses CWE-798
Type Values Removed Values Added
Weaknesses CWE-200
CWE-639
Type Values Removed Values Added
First Time appeared Curl
Curl curl
Vendors & Products Curl
Curl curl
Type Values Removed Values Added
Weaknesses CWE-200
CWE-639
Type Values Removed Values Added
Description 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`.
Title cross-origin Digest auth state leak
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
curl
Published
Updated
Sep 15, 2026, 6:02 AM
Reserved
Jun 10, 2026, 8:59 AM
Status
Modified
Published
Jul 3, 2026, 7:16 AM
Modified
Sep 15, 2026, 7:16 AM
Severity
Moderate
Public date
Jul 3, 2026, 6:13 AM