CVE-2026-6276
Last modified
CVE-2026-6276 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.. EPSS estimates a 0.29% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Haxx | Curl | >= 7.71.0, < 8.20.0 |
References
- https://curl.se/docs/CVE-2026-6276.htmlPatch, Vendor Advisory
- https://hackerone.com/reports/3671818Exploit, Issue Tracking, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2026/04/29/13Mailing List, Third Party Advisory
- https://hackerone.com/reports/3671818Exploit, Issue Tracking, Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
Frequently Asked Questions
What is CVE-2026-6276?
How severe is CVE-2026-6276?
How do I fix CVE-2026-6276?
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.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
Related CVEs from 2026
- CVE-2026-62752Heap-based buffer overflow in Windows Kerberos allows an aut…7.8
- CVE-2026-62753Heap-based buffer overflow in Windows HTTP.sys allows an aut…7
- CVE-2026-62754Heap-based buffer overflow in Windows Kerberos allows an aut…7.8
- CVE-2026-62755Stack-based buffer overflow in Windows DHCP Client allows an…7.8
- CVE-2026-62757Improper verification of cryptographic signature in Windows …5.3
- CVE-2026-62758Heap-based buffer overflow in Windows Remote Access Connecti…7.8
- CVE-2026-62761Improper link resolution before file access ('link following…7.8
- CVE-2026-62764Improper Handling of Insufficient Privileges vulnerability i…6.5
- CVE-2026-62766Double free in Windows Kerberos allows an authorized attacke…7
- CVE-2026-62768Stack-based buffer overflow in Windows Installer allows an a…7.8
- CVE-2026-62769Numeric truncation error in Windows DNS allows an authorized…6.7
- CVE-2026-6277GitLab has remediated an issue in GitLab EE affecting all ve…4.3
Are you affected by CVE-2026-6276?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST