CVE-2026-80255

secure cookie attribute bypass with tab

Published Sep 6, 2026 CVSS 3.1 · 7.5 High EPSS < 1% KEV · Not listed
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

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Ubuntu USN Ubuntu USN USN-8820-1 curl vulnerabilities
History
Type Values Removed Values Added
First Time appeared Haxx
Haxx curl
CPEs cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*
Vendors & Products Haxx
Haxx curl
Type Values Removed Values Added
Weaknesses CWE-1024
Type Values Removed Values Added
Weaknesses CWE-201
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Curl
Curl curl
Vendors & Products Curl
Curl curl
Type Values Removed Values Added
Weaknesses CWE-1024
Type Values Removed Values Added
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.
Title secure cookie attribute bypass with tab
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
curl
Published
Updated
Sep 15, 2026, 6:03 AM
Reserved
Aug 26, 2026, 6:25 AM
Status
Modified
Published
Sep 6, 2026, 6:17 PM
Modified
Sep 15, 2026, 7:16 AM
Severity
Low
Public date
Sep 6, 2026, 5:48 PM