CVE-2026-82209

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`).

CVSS v3 8.2 HIGH

8.2^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 4.2

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact LOW

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://curl.se/docs/CVE-2026-82209.html	Patch Vendor Advisory
https://curl.se/docs/CVE-2026-82209.json	Vendor Advisory
https://hackerone.com/reports/3972385	Exploit Mitigation Third Party Advisory
https://hackerone.com/reports/3972385	Exploit Mitigation Third Party Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-09-06 18:17

Updated : 2026-09-15 07:16

NVD link : CVE-2026-82209

Mitre link : CVE-2026-82209

CVE.ORG link : CVE-2026-82209

JSON object : View

Products Affected

haxx

curl

CWE

CWE-201

Insertion of Sensitive Information Into Sent Data

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"CWE-201"}]}], "descriptions": [{"lang": "en", "value": "When libpsl support is enabled, libcurl fails to enforce the Public Suffix\nList boundary check when processing a `Set-Cookie` header where the `Domain`\nattribute explicitly matches an origin host that is itself a public suffix\n(e.g., `Domain=co.uk` set by `co.uk`).\n\nInstead of coercing it into a strict host-only cookie, libcurl saves the\ncookie with wildcard domain scope (`.co.uk`). Consequently, the cookie is\ninappropriately included in subsequent outbound requests or HTTP redirects to\narbitrary sibling subdomains under the same public suffix (e.g.,\n`attacker.co.uk`)."}], "lastModified": "2026-09-15T07:16:31.233", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:haxx:curl:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "90DD0BCD-CC3E-479C-9720-399378C87E00", "versionEndExcluding": "8.22.0", "versionStartIncluding": "7.46.0"}], "operator": "OR"}]}], "sourceIdentifier": "2499f714-1537-4658-8207-48ae4bb9eae9"}