curl Set-Cookie Tab Before Secure Flag Causes Unsecured Cookie Storage
CVE-2026-80255 Published on September 6, 2026

secure cookie attribute bypass with tab
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.

NVD

Vulnerability Analysis

CVE-2026-80255 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. An automatable proof of concept (POC) exploit exists. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
HIGH
Integrity Impact:
NONE
Availability Impact:
NONE

Weakness Type

Insertion of Sensitive Information Into Sent Data

The code transmits data to another actor, but a portion of the data includes sensitive information that should not be accessible to that actor. Sensitive information could include data that is sensitive in and of itself (such as credentials or private messages), or otherwise useful in the further exploitation of the system (such as internal file system structure).


Products Associated with CVE-2026-80255

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Haxx Curl
 

Affected Versions

curl: curl: curl: