Vulnerability · Published Sep 6, 2026 · Assigned by curl
CVE-2026-82209domain-scoped PSL domain cookie
High 8.2
In plain English
A high-severity security flaw in curl from curl. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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 packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | curl | 8.22.0-r0 | ALPINE-CVE-2026-82209 |
| Alpine:v3.24 | curl | 8.22.0-r0 | ALPINE-CVE-2026-82209 |
| Debian:12 | curl | no fix listed | DEBIAN-CVE-2026-82209 |
| Debian:13 | curl | no fix listed | DEBIAN-CVE-2026-82209 |
| Debian:14 | curl | 8.22.0-1 | DEBIAN-CVE-2026-82209 |
| Ubuntu:22.04:LTS | curl | 7.81.0-1ubuntu1.29 | UBUNTU-CVE-2026-82209 |
| Ubuntu:22.04:LTS | curl | 7.81.0-1ubuntu1.29 | USN-8820-1 |
| Ubuntu:24.04:LTS | curl | 8.5.0-2ubuntu10.15 | USN-8820-1 |
| Ubuntu:24.04:LTS | curl | 8.5.0-2ubuntu10.15 | UBUNTU-CVE-2026-82209 |
| Ubuntu:26.04:LTS | curl | 8.18.0-1ubuntu2.7 | USN-8820-1 |
| Ubuntu:26.04:LTS | curl | 8.18.0-1ubuntu2.7 | UBUNTU-CVE-2026-82209 |
| Ubuntu:26.10 | curl | 8.20.0-2ubuntu11 | UBUNTU-CVE-2026-82209 |
Affected products (as reported)
Weakness: CWE-201 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N