CVE-2026-82209: domain-scoped PSL domain cookie
domain-scoped PSL domain cookie
Other sources
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).
— Launchpad
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/curlto a version that resolves this vulnerability.Fixed in 8.22.0-1Fixed in 8.23.0~rc1-2
Event History
Frequently Asked Questions
Who is exposed to this issue?
Applications using libcurl with libpsl support enabled are exposed when they accept cookies from an origin host that is itself a public suffix. The affected cookie can then be sent to sibling subdomains under that suffix.
What does an attacker need to exploit it?
An attacker needs a situation where a response from a public-suffix origin can set a cookie with a Domain attribute explicitly matching that origin, such as Domain=co.uk. The resulting cookie may be included in requests or redirects to arbitrary sibling subdomains, such as attacker.co.uk.
Are cookies from ordinary registrable domains affected?
The described behavior specifically concerns an origin host that is itself a public suffix and a Domain attribute matching that public-suffix host. The provided information does not indicate that ordinary registrable-domain cookie handling is affected.