CVE-2026-8924
Description
A flaw was found in curl's cookie parsing logic. A malicious HTTP server can exploit this by setting 'super cookies' that bypass the Public Suffix List check. This allows an attacker-controlled origin to inject cookies that curl then transmits to unrelated third-party domains, leading to compromising request integrity.
Statement
Moderate: Red Hat rates this flaw Moderate (CVSS 6.5) compared to CISA's Critical (9.1). The scoring difference is due to two factors: first, exploitation requires the victim's curl to connect using a trailing-dot hostname (e.g., https://example.co.uk.), a format that is uncommon in practice and incompatible with TLS SNI; second, the direct impact is cookie injection into outbound requests — not exfiltration of victim data to the attacker. The curl project itself rates this flaw Low severity. Red Hat products that use curl for HTTP communication are affected, but the trailing-dot precondition significantly limits real-world exploitability. This flaw has not been shown to enable impacts beyond session integrity modification.
Mitigation
Do not use trailing-dot hostnames in URLs passed to curl. Trailing dots are uncommon and incompatible with TLS SNI. Upgrade to curl 8.21.0 to resolve
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 6.5 | N/A | 9.1 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | None | N/A | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N
Understanding the Weakness (CWE)
Confidentiality,Integrity,Availability
Technical Impact: Modify Application Data; Execute Unauthorized Code or Commands
Attackers can easily modify cookies, within the browser or by implementing the client-side code outside of the browser. Reliance on cookies without detailed validation and integrity checking can allow attackers to bypass authentication, conduct injection attacks such as SQL injection and cross-site scripting, or otherwise modify inputs in unexpected ways.
Access Control
Technical Impact: Gain Privileges or Assume Identity
It is dangerous to use cookies to set a user's privileges. The cookie can be manipulated to escalate an attacker's privileges to an administrative level.
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