CVE-2026-82209

domain-scoped PSL domain cookie

HIGH
8.2
CVSS Score
Published: September 6, 2026 at 05:49 PM UTC
Updated: September 15, 2026 at 07:35 AM UTC
1 product affected across 1 vendorCurl

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Severity
HIGH8.2
Exploit prediction
EPSS 0.4%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Vendor states this is fixed in 95c1e8915dce64606bd753fd47fc0bd236e31cd6 (fixed)
Affected range stops below 8.14.2, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.16.1, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.20.1, so it looks safe — our inference, not a vendor statement
Affected range stops below 8.22.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (3)

Vendor Advisory
Source: cverecord
https://curl.se/docs/CVE-2026-82209.json
PatchVendor Advisory
Source: cverecord
https://curl.se/docs/CVE-2026-82209.html
ExploitMitigationThird Party Advisory
Source: cverecord
https://hackerone.com/reports/3972385

SSVC — Action Prioritization

SSVCPoCAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.2HIGHCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-201

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