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Vulnerability record · CVE-2026-82209 · published 6 September 2026

CVE-2026-82209: Haxx curl vulnerability

Haxx · Curl

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`).

8.2 CVSS 3.1 High EPSS 0.37% · top 71.3% CWE-201 · CWE-201
8.2CVSS 3.1 base score
0.37%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
4References, 2 tagged exploit
15 Sep 2026Last modified by NVD

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`).

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-82209), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.