CVE-2021-4209
MEDIUMCVSS 6.5/10EPSS 1.38%
Last modified
CVE-2021-4209 is a medium-severity vulnerability rated 6.5/10 on the CVSS scale. A NULL pointer dereference flaw was found in GnuTLS. As Nettle's hash update functions internally call memcpy, providing zero-length input may cause undefined behavior. EPSS estimates a 1.38% chance of exploitation in the next 30 days.
Description
A NULL pointer dereference flaw was found in GnuTLS. As Nettle's hash update functions internally call memcpy, providing zero-length input may cause undefined behavior. This flaw leads to a denial of service after authentication in rare circumstances.
Metrics
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Gnu | Gnutls | < 3.7.3 |
| Redhat | Enterprise Linux | 8.0 |
| Netapp | Active Iq Unified Manager | All versions |
| Netapp | Solidfire \& Hci Management Node | All versions |
| Netapp | Hci Bootstrap Os | All versions |
References
- https://access.redhat.com/security/cve/CVE-2021-4209Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2044156Issue Tracking, Third Party Advisory
- https://gitlab.com/gnutls/gnutls/-/commit/3db352734472d851318944db13be73da61300568Patch, Third Party Advisory
- https://gitlab.com/gnutls/gnutls/-/issues/1306Third Party Advisory
- https://gitlab.com/gnutls/gnutls/-/merge_requests/1503Third Party Advisory
- https://security.netapp.com/advisory/ntap-20220915-0005/Third Party Advisory
- https://access.redhat.com/security/cve/CVE-2021-4209Third Party Advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=2044156Issue Tracking, Third Party Advisory
- https://gitlab.com/gnutls/gnutls/-/commit/3db352734472d851318944db13be73da61300568Patch, Third Party Advisory
- https://gitlab.com/gnutls/gnutls/-/issues/1306Third Party Advisory
- https://gitlab.com/gnutls/gnutls/-/merge_requests/1503Third Party Advisory
- https://security.netapp.com/advisory/ntap-20220915-0005/Third Party Advisory
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2021-4209?
A NULL pointer dereference flaw was found in GnuTLS. As Nettle's hash update functions internally call memcpy, providing zero-length input may cause undefined behavior. This flaw leads to a denial of service after authentication in rare circumstances.
How severe is CVE-2021-4209?
CVE-2021-4209 has a CVSS score of 6.5/10 (MEDIUM severity). The EPSS model estimates a 1.38% probability of exploitation in the next 30 days.
How do I fix CVE-2021-4209?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-4209?
Run a free Strix scan to check your systems for this vulnerability.
Scan your code nowSource: NVD / NIST