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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…
Medium6.5EPSS 1.9%
- Published
- Updated
- Reserved
- Assigned by
- redhat
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.
Timeline
ID reserved
By redhat
- 7 months later
· 7 months later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Modified | 3.1 | Medium6.5 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
- EPSS (exploitation in 30 days)
- 1.9% · top 20% of all CVEs (7 Nov 2026)
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.5.
Weakness
Affected products
GnuTLS
- affected Fixed in gnutls v3.7.3
References (7)
- https://gitlab.com/gnutls/gnutls/-/issues/1306 (opens in a new tab)x_refsource_MISCx_transferred
- https://bugzilla.redhat.com/show_bug.cgi?id=2044156 (opens in a new tab)x_refsource_MISCx_transferred
- https://access.redhat.com/security/cve/CVE-2021-4209 (opens in a new tab)x_refsource_MISCx_transferred
- https://gitlab.com/gnutls/gnutls/-/merge_requests/1503 (opens in a new tab)x_refsource_MISCx_transferred
- https://gitlab.com/gnutls/gnutls/-/commit/3db352734472d851318944db13be73da61300568 (opens in a new tab)x_refsource_MISCx_transferred
- https://security.netapp.com/advisory/ntap-20220915-0005/ (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://cert-portal.siemens.com/productcert/html/ssa-398330.html (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2021-4209)Record last updated .