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CVE-2026-80255

7.5 · HIGH

A `Set-Cookie:` header using tab (horizontal tab, ASCII code 9) instead of space (ascii code 32) immediately before the `Secure` attribute causes curl to store the cookie without its Secure flag.

Published Sep 6, 2026haxxCWE-201EPSS 0.48%

Overview

CVE-2026-80255 is a high-severity vulnerability affecting haxx curl. It was published on September 6, 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

A `Set-Cookie:` header using tab (horizontal tab, ASCII code 9) instead of

space (ascii code 32) immediately before the `Secure` attribute causes curl to

store the cookie without its Secure flag. The cookie might then wrongfully be

sent over plaintext HTTP on subsequent requests to the same host.

Remediation

Check the references section for vendor advisories and patches from haxx. Update curl to the latest patched version. 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.

Affected products

VendorProductVersionsStatus
haxxcurl>= 8.13.0, < 8.22.0Affected

References

Refcurl.se/docs/CVE-2026-80255.htmlRefcurl.se/docs/CVE-2026-80255.jsonRefhackerone.com/reports/3972395Refhackerone.com/reports/3972395

How CyberStrike helps

Frequently asked questions

What is CVE-2026-80255?

CVE-2026-80255 is a high-severity vulnerability affecting haxx curl. It was published on September 6, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-80255?

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-2026-80255?

Check the references section for vendor advisories and patches from haxx. Update curl to the latest patched version. 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-2026-80255?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-80255 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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