What’s Vulnerable › Vulnerabilities

CVE-2026-82209: domain-scoped PSL domain cookie

• Severity: high (CVSS 8.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-09-06 · updated 2026-09-15
• Weakness: CWE-201

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`).

Affected products

• curl: from 7.46.0 before 8.22.0 — fixed in 8.22.0

How to fix

Upgrade to a fixed version: curl 8.22.0. Check the vendor advisory for mitigations.

References

• https://curl.se/docs/CVE-2026-82209.html
• https://curl.se/docs/CVE-2026-82209.json
• https://hackerone.com/reports/3972385
• https://hackerone.com/reports/3972385

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