Vulnerability · Published Sep 6, 2026 · Assigned by curl
CVE-2026-80255secure cookie attribute bypass with tab
High 7.5
In plain English
A high-severity security flaw in curl from curl. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 41% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.5%top 58.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | curl | 8.22.0-r0 | ALPINE-CVE-2026-80255 |
| Alpine:v3.24 | curl | 8.22.0-r0 | ALPINE-CVE-2026-80255 |
| Debian:13 | curl | no fix listed | DEBIAN-CVE-2026-80255 |
| Debian:14 | curl | 8.22.0-1 | DEBIAN-CVE-2026-80255 |
| Ubuntu:22.04:LTS | curl | 7.81.0-1ubuntu1.29 | USN-8820-1 |
| Ubuntu:24.04:LTS | curl | 8.5.0-2ubuntu10.15 | USN-8820-1 |
| Ubuntu:26.04:LTS | curl | 8.18.0-1ubuntu2.7 | USN-8820-1 |
| Ubuntu:26.04:LTS | curl | 8.18.0-1ubuntu2.7 | UBUNTU-CVE-2026-80255 |
| Ubuntu:26.10 | curl | 8.20.0-2ubuntu11 | UBUNTU-CVE-2026-80255 |
Affected products (as reported)
Weakness: CWE-201 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N