CVE-2026-41940 — Watchtowrlabs
CRITICALCVE-2026-41940 is a critical-severity (CVSS 9.8) Missing Authentication vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2026-04-30) and has been used in ransomware campaigns — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.
cPanel and WHM versions after 11.40 contain an authentication bypass vulnerability in the login flow that allows unauthenticated remote attackers to gain unauthorized access to the control panel.
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2026-04-30 — including use in ransomware campaigns. Federal agencies were required to remediate by 2026-05-03.
- 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 (KEV catalog and SSVC triage) for CVE-2026-41940.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-41940 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).
Where this sits among everything scored
Of 395,249 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Counts from FIRST.org, log-scaled.
Description
cPanel and WHM versions after 11.40 contain an authentication bypass vulnerability in the login flow that allows unauthenticated remote attackers to gain unauthorized access to the control panel.
Affected Products
cpanelcpanelwhmcpanelwp squaredcpanelResearch use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
cPanel - CRLF Injection
by nu11secur1ty · May 26, 2026
Detection & 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`).
Remediation status
No fixed release is recorded for CVE-2026-41940 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.
Mitigate without a patch
Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.
How to detect CVE-2026-41940
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2026-41940 -u https://target- Template
- cPanel & WHM - Authentication Bypass via Session-File CRLF Injection
- Severity
- critical
- Impact
- Unauthenticated remote attackers can gain unauthorized access to the control panel, compromising system security.
- Remediation
- Update to version 11.110.0.97, 11.118.0.63, 11.126.0.54, 11.132.0.29, 11.134.0.20, 11.136.0.5 or later.
Template by ProjectDiscovery nuclei-templates (watchtowr, hadrian.io, DhiyaneshDk), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2026-41940 in your dependencies?
Find it across , including transitive dependencies.