CVE-2026-8924 — curl
CRITICALCVE-2026-8924 is a critical-severity (CVSS 9.1) CWE-201 vulnerability. A fix is available — see the affected versions and patch details below.
trailing dot domain super cookie
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-8924.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Description
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.
Affected Products
curlhaxxDetection & mitigation playbook
VulnerabilityDetect
Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).
Fix
Upgrade the affected component to the fixed release for CVE-2026-8924, or apply your distribution's backported patch — distro builds are often patched at an older version number, so check your vendor's advisory rather than the upstream version alone.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Moderate: Red Hat rates this flaw Moderate (CVSS 6.5) compared to CISA's Critical (9.1). The scoring difference is due to two factors: first, exploitation requires the victim's curl to connect using a trailing-dot hostname (e.g., https://example.co.uk.), a format that is uncommon in practice and incompatible with TLS…
Do not use trailing-dot hostnames in URLs passed to curl. Trailing dots are uncommon and incompatible with TLS SNI. Upgrade to curl 8.21.0 to resolveSource: Red Hat security advisory for CVE-2026-8924 (CC BY 4.0)
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | curl-0:8.12.1-4.el10_2.6 | RHSA-2026:69125 |
| Red Hat Enterprise Linux 10.0 Extended Update Support | curl-0:8.12.1-1.el10_0.10 | RHSA-2026:72506 |
| Red Hat Enterprise Linux 8 | curl-0:7.61.1-34.el8_10.18 | RHSA-2026:92368 |
| Red Hat Enterprise Linux 9 | curl-0:7.76.1-40.el9_8.8 | RHSA-2026:80511 |
| Red Hat Enterprise Linux 9.6 Extended Update Support | curl-0:7.76.1-31.el9_6.4 | RHSA-2026:93454 |
| Red Hat JBoss Core Services 2.4.62.SP5 | see advisory | RHSA-2026:56869 |
| Red Hat OpenShift Container Platform 4.22 | openshift/ose-rhel-coreos-9:4.22.9.8.202610241758-0 | RHSA-2026:89197 |
| Red Hat Satellite 6.16 for RHEL 8 | openvox-agent-0:8.31.1-1.el8sat | RHSA-2026:92858 |
Frequently Asked Questions
Is CVE-2026-8924 in your dependencies?
Find it across your dependency tree, including transitive dependencies.