What is CVE-2026-8924?

CVE-2026-8924 is a critical-severity vulnerability in Curl, classified under Insertion of Sensitive Information into Sent Data. CVSS score: 9.1/10. Published 2026-07-03.

How severe is CVE-2026-8924?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Vulnerability in Curl

CVE-2026-8924

A flaw in curl’s cookie parsing logic allows a malicious HTTP server to set "super cookies" that bypass the Public Suffix List check. This enables an attacker-controlled origin to inject cookies that curl subsequently scopes and transmits to unrelated third-party domains.

Published 2026-07-03 · last modified 2026-09-15.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N.

EPSS exploit prediction

EPSS: 0.007 (49.8th percentile), scored 2026-10-02.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 50th percentile — 49.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.006 · newest: 0.007 · change: +0.001

Affected products

Curl — versions 8.20.0, 8.19.0, 8.18.0
Haxx Curl

Weakness classification (CWE)

CWE-201 — Insertion of Sensitive Information into Sent Data

References

2499f714-1537-4658-8207-48ae4bb9eae9 (Vendor Advisory)
2499f714-1537-4658-8207-48ae4bb9eae9 (Patch, Vendor Advisory)
2499f714-1537-4658-8207-48ae4bb9eae9 (Exploit, Third Party Advisory, Issue Tracking)

Frequently asked questions

What is CVE-2026-8924?: CVE-2026-8924 is a critical-severity vulnerability in Curl, classified under Insertion of Sensitive Information into Sent Data. CVSS score: 9.1/10. Published 2026-07-03.
How severe is CVE-2026-8924?: Critical severity. CVSS v3 base score is 9.1 out of 10.