CVE-2026-11856
Last modified
CVE-2026-11856 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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`.. EPSS estimates a 0.75% chance of exploitation in the next 30 days.
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`.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Haxx | Curl | >= 7.10.6, < 8.21.0 |
References
- https://curl.se/docs/CVE-2026-11856.htmlPatch, Vendor Advisory
- https://curl.se/docs/CVE-2026-11856.jsonVendor Advisory
- https://hackerone.com/reports/3793260Exploit, Issue Tracking, Third Party Advisory
- https://hackerone.com/reports/3793260Exploit, Issue Tracking, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
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How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
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