What’s Vulnerable › Vulnerabilities

CVE-2026-80255: secure cookie attribute bypass with tab

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-09-06 · updated 2026-09-15
• Weakness: CWE-201

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.

Affected products

• curl: from 8.13.0 before 8.22.0 — fixed in 8.22.0

How to fix

Upgrade to a fixed version: curl 8.22.0. Check the vendor advisory for mitigations.

References

• https://curl.se/docs/CVE-2026-80255.html
• https://curl.se/docs/CVE-2026-80255.json
• https://hackerone.com/reports/3972395
• https://hackerone.com/reports/3972395

Get alerted when CVE-2026-80255 or the next vulnerability affects your stack