High 7.5Published Sep 6, 2026

CVE-2026-80255secure cookie attribute bypass with tab

Updated under an hour ago (2026-10-19 08:00 UTC)

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It affects curl and 1 other product. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

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.

CVSS: 7.5 HIGH (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness (CWE): CWE-201
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: curl
NVD analysis: Modified
Record last updated: Sep 15, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

curl curl curl:curl (from the name)	from 8.13.0 before 8.14.2; from 8.15.0 before 8.16.1; from 8.17.0 before 8.20.1; from 8.21.0 before 8.22.0	CNA record
haxx curl haxx:curl	from 8.13.0 before 8.22.0	NVD

References

https://curl.se/docs/CVE-2026-80255.jsonvendor-advisory
https://curl.se/docs/CVE-2026-80255.htmlpatch, vendor-advisory
https://hackerone.com/reports/3972395exploit, mitigation, third-party-advisory

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.