Reference page — cumulative record through Sunday, October 4, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-80255

CVE-2026-80255HIGH

curl curl — secure cookie attribute bypass with tab

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  U  H  N  N    7.5   .0048   39.1     —

AFFECTED
  Product  Versions                                    Fixed
  curl     8.13.0 –                                    —
  curl     1aea05a6c2699e80c75936d58569851555acd603 –  —
  curl     8.21.0 –                                    —

TIMELINE
  Aug 26  Reserved by curl
  Sep 6   Published (CNA: curl)
  Sep 11  EXPLOIT PUBLISHED — CVE-2026-80255 (curl). Public exploit reference added.
  Sep 15  EXPLOIT PUBLISHED — CVE-2026-80255 (curl). Public exploit reference added.

CWE-201 · CNA: curl · CVSS v3.1 · 3 references · NVD status: Modified

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.

Lifecycle

Complete event history — 4 events, chronological
Date	Event	Detail
August 26, 2026	Reserved	Reserved by curl
September 6, 2026	Published	Published (CNA: curl)
September 11, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-80255 (curl). Public exploit reference added.
September 15, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-80255 (curl). Public exploit reference added.

Affected

Affected products and packages — 3 rows
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
curl	curl	—	8.13.0	—
curl	curl	—	1aea05a6c2699e80c75936d58569851555acd603	—
curl	curl	—	8.21.0	—

Weaknesses

CWE-201

References (3)

https://curl.se/docs/CVE-2026-80255.html [Patch, Vendor Advisory]
https://curl.se/docs/CVE-2026-80255.json [Vendor Advisory]
https://hackerone.com/reports/3972395 [Exploit, Mitigation, Third Party Advisory]

Authoritative record: CVE-2026-80255 at cve.org

Vendors: curl

Weaknesses: CWE-201

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-80255 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Sunday, October 4, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.