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CVE-2026-6276

7.5 · HIGH

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 se…

Published May 13, 2026CWE-319EPSS 0.35%

Overview

CVE-2026-6276 is a high-severity vulnerability. It was published on May 13, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refcurl.se/docs/CVE-2026-6276.htmlRefcurl.se/docs/CVE-2026-6276.jsonRefhackerone.com/reports/3671818Refwww.openwall.com/lists/oss-security/2026/04/29/13Refhackerone.com/reports/3671818

How CyberStrike helps

Frequently asked questions

What is CVE-2026-6276?

CVE-2026-6276 is a high-severity vulnerability. It was published on May 13, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-6276?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-6276?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-6276?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-6276 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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