Description
When libpsl support is enabled, libcurl fails to enforce the Public Suffix
List boundary check when processing a `Set-Cookie` header where the `Domain`
attribute explicitly matches an origin host that is itself a public suffix
(e.g., `Domain=co.uk` set by `co.uk`).

Instead of coercing it into a strict host-only cookie, libcurl saves the
cookie with wildcard domain scope (`.co.uk`). Consequently, the cookie is
inappropriately included in subsequent outbound requests or HTTP redirects to
arbitrary sibling subdomains under the same public suffix (e.g.,
`attacker.co.uk`).
Published: 2026-09-06
Score: n/a
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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History

Sun, 06 Sep 2026 19:45:00 +0000

Type Values Removed Values Added
First Time appeared Curl
Curl curl
Weaknesses CWE-20
Vendors & Products Curl
Curl curl

Sun, 06 Sep 2026 18:00:00 +0000

Type Values Removed Values Added
Description When libpsl support is enabled, libcurl fails to enforce the Public Suffix List boundary check when processing a `Set-Cookie` header where the `Domain` attribute explicitly matches an origin host that is itself a public suffix (e.g., `Domain=co.uk` set by `co.uk`). Instead of coercing it into a strict host-only cookie, libcurl saves the cookie with wildcard domain scope (`.co.uk`). Consequently, the cookie is inappropriately included in subsequent outbound requests or HTTP redirects to arbitrary sibling subdomains under the same public suffix (e.g., `attacker.co.uk`).
Title domain-scoped PSL domain cookie
References

cve-icon MITRE

Status: PUBLISHED

Assigner: curl

Published:

Updated: 2026-09-06T17:49:35.050Z

Reserved: 2026-08-28T08:25:48.340Z

Link: CVE-2026-82209

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-06T18:17:22.847

Modified: 2026-09-06T18:17:22.847

Link: CVE-2026-82209

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-06T19:30:11Z

Weaknesses
  • CWE-20

    Improper Input Validation