CVE catalog

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

[CVE catalog]

Severity: Medium · CVSS 6.5CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Published: Feb 22, 2022, 8:07:00 PM UTC
Updated: Oct 14, 2026, 11:16:55 AM UTC
Source: [NVD] · [CVE record]
EPSS: 1.91% · Oct 25, 2026

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.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	gnutls28	sid	`3.8.13-1`	fixed
Debian	gnutls28	forky	`3.8.13-1`	fixed
Debian	gnutls28	trixie	`3.8.9-3+deb13u4`	fixed
Debian	gnutls28	trixie-security	`3.8.9-3+deb13u4`	fixed
Debian	gnutls28	bookworm	`3.7.9-2+deb12u7`	fixed
Debian	gnutls28	bookworm-security	`3.7.9-2+deb12u7`	fixed
Cpe	gnutls	Not reported	`3.7.3`	fixed
Cpe	enterprise_linux	Not reported	Not reported	unknown
Cpe	active_iq_unified_manager	Not reported	Not reported	unknown
Cpe	solidfire_\&_hci_management_node	Not reported	Not reported	unknown
Cpe	hci_bootstrap_os	Not reported	Not reported	unknown
Ubuntu	gnutls26	pro	`2.12.23-1ubuntu4`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-1ubuntu5`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-12ubuntu1`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-12ubuntu2`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-12ubuntu2.1`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-12ubuntu2.2`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-12ubuntu2.3`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-12ubuntu2.4`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-12ubuntu2.5`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-12ubuntu2.6`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-12ubuntu2.7`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-12ubuntu2.8`	vulnerable
Ubuntu	gnutls26	pro	`2.12.23-12ubuntu2.10+esm1`	vulnerable
Ubuntu	gnutls28	pro	`3.3.15-5ubuntu2`	vulnerable
Ubuntu	gnutls28	pro	`3.3.18-1ubuntu1`	vulnerable
Ubuntu	gnutls28	pro	`3.3.20-1ubuntu1`	vulnerable
Ubuntu	gnutls28	pro	`3.4.9-2ubuntu1`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.1`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.2`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.3`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.4`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.5`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.6`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.7`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.8`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.9`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.9+esm1`	fixed
Ubuntu	gnutls28	18.04	`3.5.8-6ubuntu3`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.17-1ubuntu1`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.17-1ubuntu3`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.1`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.2`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.3`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.4`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.5`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.6`	fixed
Ubuntu	gnutls28	20.04	`3.6.9-5ubuntu1`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.9-5ubuntu2`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.10-5`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.11.1-2`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.11.1-2ubuntu2`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1.1`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1.2`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1.3`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1.6`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1.7`	fixed
Ubuntu	gnutls28	pro	`3.3.15-5ubuntu2`	vulnerable
Ubuntu	gnutls28	pro	`3.3.18-1ubuntu1`	vulnerable
Ubuntu	gnutls28	pro	`3.3.20-1ubuntu1`	vulnerable
Ubuntu	gnutls28	pro	`3.4.9-2ubuntu1`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.1`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.2`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.3`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.4`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.5`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.6`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.7`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.8`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.9`	vulnerable
Ubuntu	gnutls28	pro	`3.4.10-4ubuntu1.9+esm1`	fixed
Ubuntu	gnutls28	18.04	`3.5.8-6ubuntu3`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.17-1ubuntu1`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.17-1ubuntu3`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.1`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.2`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.3`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.4`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.5`	vulnerable
Ubuntu	gnutls28	18.04	`3.5.18-1ubuntu1.6`	fixed
Ubuntu	gnutls28	20.04	`3.6.9-5ubuntu1`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.9-5ubuntu2`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.10-5`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.11.1-2`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.11.1-2ubuntu2`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1.1`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1.2`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1.3`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1.6`	vulnerable
Ubuntu	gnutls28	20.04	`3.6.13-2ubuntu1.7`	fixed
Ubuntu	gnutls28	22.04	`3.7.1-5ubuntu1`	vulnerable
Ubuntu	gnutls28	22.04	`3.7.2-2ubuntu1`	vulnerable
Ubuntu	gnutls28	22.04	`3.7.2-4ubuntu1`	vulnerable
Ubuntu	gnutls28	22.04	`3.7.2-5ubuntu1`	vulnerable
Ubuntu	gnutls28	22.04	`3.7.3-4ubuntu1`	vulnerable
Ubuntu	gnutls28	22.04	`3.7.3-4ubuntu1.1`	fixed
Suse	gnutls	linux enterprise server 12 sp5	`3.4.17-8.11.1`	fixed
Suse	gnutls	linux enterprise server for sap applications 12 sp5	`3.4.17-8.11.1`	fixed
Suse	gnutls	linux enterprise module for basesystem 15 sp3	`3.6.7-14.16.1`	fixed
Suse	gnutls	linux enterprise real time 15 sp2	`3.6.7-14.16.1`	fixed
Suse	gnutls	linux enterprise micro 5.0	`3.6.7-14.16.1`	fixed
Suse	gnutls	linux enterprise micro 5.1	`3.6.7-14.16.1`	fixed
Opensuse	gnutls	leap 15.3	`3.6.7-14.16.1`	fixed
Suse	gnutls	linux enterprise software development kit 12 sp5	`3.3.27-3.6.1`	fixed
Suse	gnutls	linux enterprise server 12 sp5	`3.3.27-3.6.1`	fixed
Suse	gnutls	linux enterprise server for sap applications 12 sp5	`3.3.27-3.6.1`	fixed
Suse	gnutls	linux enterprise high performance computing 15-espos	`3.6.7-150000.6.45.2`	fixed
Suse	gnutls	linux enterprise high performance computing 15-ltss	`3.6.7-150000.6.45.2`	fixed
Suse	gnutls	linux enterprise high performance computing 15 sp1-espos	`3.6.7-150000.6.45.2`	fixed
Suse	gnutls	linux enterprise high performance computing 15 sp1-ltss	`3.6.7-150000.6.45.2`	fixed
Suse	gnutls	linux enterprise server 15-ltss	`3.6.7-150000.6.45.2`	fixed
Suse	gnutls	linux enterprise server 15 sp1-bcl	`3.6.7-150000.6.45.2`	fixed
Suse	gnutls	linux enterprise server 15 sp1-ltss	`3.6.7-150000.6.45.2`	fixed
Suse	gnutls	linux enterprise server for sap applications 15	`3.6.7-150000.6.45.2`	fixed
Suse	gnutls	linux enterprise server for sap applications 15 sp1	`3.6.7-150000.6.45.2`	fixed
Suse	gnutls	enterprise storage 6	`3.6.7-150000.6.45.2`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	gnutls28	source	sid	`3.7.3-2`	not yet assigned	Not reported	Not reported
Debian	gnutls28	source	forky	`3.7.3-2`	not yet assigned	Not reported	Not reported
Debian	gnutls28	source	trixie	`3.7.3-2`	not yet assigned	Not reported	Not reported
Debian	gnutls28	source	bookworm	`3.7.3-2`	not yet assigned	Not reported	Not reported
Cpe	gnutls	cpe	Not reported	`3.7.3`	Not reported	NVD-CVE-2021-4209	Not reported
Ubuntu	gnutls28	deb	pro	`3.4.10-4ubuntu1.9+esm1`	Not reported	UBUNTU-CVE-2021-4209	Not reported
Ubuntu	gnutls28	deb	18.04	`3.5.18-1ubuntu1.6`	Not reported	UBUNTU-CVE-2021-4209	Not reported
Ubuntu	gnutls28	deb	20.04	`3.6.13-2ubuntu1.7`	Not reported	UBUNTU-CVE-2021-4209	Not reported
Ubuntu	gnutls28	deb	pro	`3.4.10-4ubuntu1.9+esm1`	Not reported	USN-5750-1	Not reported
Ubuntu	gnutls28	deb	18.04	`3.5.18-1ubuntu1.6`	Not reported	USN-5550-1	Not reported
Ubuntu	gnutls28	deb	20.04	`3.6.13-2ubuntu1.7`	Not reported	USN-5550-1	Not reported
Ubuntu	gnutls28	deb	22.04	`3.7.3-4ubuntu1.1`	Not reported	USN-5550-1	Not reported
Suse	gnutls	rpm	linux enterprise server 12 sp5	`3.4.17-8.11.1`	Not reported	SUSE-SU-2022:0678-1	Not reported
Suse	gnutls	rpm	linux enterprise server for sap applications 12 sp5	`3.4.17-8.11.1`	Not reported	SUSE-SU-2022:0678-1	Not reported
Suse	gnutls	rpm	linux enterprise module for basesystem 15 sp3	`3.6.7-14.16.1`	Not reported	SUSE-SU-2022:0717-1	Not reported
Suse	gnutls	rpm	linux enterprise real time 15 sp2	`3.6.7-14.16.1`	Not reported	SUSE-SU-2022:0717-1	Not reported
Suse	gnutls	rpm	linux enterprise micro 5.0	`3.6.7-14.16.1`	Not reported	SUSE-SU-2022:0717-1	Not reported
Suse	gnutls	rpm	linux enterprise micro 5.1	`3.6.7-14.16.1`	Not reported	SUSE-SU-2022:0717-1	Not reported
Opensuse	gnutls	rpm	leap 15.3	`3.6.7-14.16.1`	Not reported	OPENSUSE-SU-2022:0717-1	Not reported
Suse	gnutls	rpm	linux enterprise software development kit 12 sp5	`3.3.27-3.6.1`	Not reported	SUSE-SU-2022:0677-1	Not reported
Suse	gnutls	rpm	linux enterprise server 12 sp5	`3.3.27-3.6.1`	Not reported	SUSE-SU-2022:0677-1	Not reported
Suse	gnutls	rpm	linux enterprise server for sap applications 12 sp5	`3.3.27-3.6.1`	Not reported	SUSE-SU-2022:0677-1	Not reported
Suse	gnutls	rpm	linux enterprise high performance computing 15-espos	`3.6.7-150000.6.45.2`	Not reported	SUSE-SU-2022:2830-1	Not reported
Suse	gnutls	rpm	linux enterprise high performance computing 15-ltss	`3.6.7-150000.6.45.2`	Not reported	SUSE-SU-2022:2830-1	Not reported
Suse	gnutls	rpm	linux enterprise high performance computing 15 sp1-espos	`3.6.7-150000.6.45.2`	Not reported	SUSE-SU-2022:2830-1	Not reported
Suse	gnutls	rpm	linux enterprise high performance computing 15 sp1-ltss	`3.6.7-150000.6.45.2`	Not reported	SUSE-SU-2022:2830-1	Not reported
Suse	gnutls	rpm	linux enterprise server 15-ltss	`3.6.7-150000.6.45.2`	Not reported	SUSE-SU-2022:2830-1	Not reported
Suse	gnutls	rpm	linux enterprise server 15 sp1-bcl	`3.6.7-150000.6.45.2`	Not reported	SUSE-SU-2022:2830-1	Not reported
Suse	gnutls	rpm	linux enterprise server 15 sp1-ltss	`3.6.7-150000.6.45.2`	Not reported	SUSE-SU-2022:2830-1	Not reported
Suse	gnutls	rpm	linux enterprise server for sap applications 15	`3.6.7-150000.6.45.2`	Not reported	SUSE-SU-2022:2830-1	Not reported
Suse	gnutls	rpm	linux enterprise server for sap applications 15 sp1	`3.6.7-150000.6.45.2`	Not reported	SUSE-SU-2022:2830-1	Not reported
Suse	gnutls	rpm	enterprise storage 6	`3.6.7-150000.6.45.2`	Not reported	SUSE-SU-2022:2830-1	Not reported

OpenFactory catalog packages

Matching against OpenFactory catalog package versions is in progress.

[Debian 12 (Bookworm)]

[gnutls-bin]Unknown
Source package: [gnutls28]
Details (4)
- 3.7.9-2+deb12u7 · amd64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · amd64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
[gnutls-doc]Unknown
Source package: [gnutls28]
Details (4)
- 3.7.9-2+deb12u7 · all · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · all · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · all · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · all · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
[guile-gnutls]Unknown
Source package: [gnutls28]
Details (4)
- 3.7.9-2+deb12u7 · amd64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · amd64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
[libgnutls28-dev]Unknown
Source package: [gnutls28]
Details (4)
- 3.7.9-2+deb12u7 · amd64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · amd64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
[libgnutls30]Unknown
Source package: [gnutls28]
Details (4)
- 3.7.9-2+deb12u7 · amd64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · amd64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
[libgnutls-dane0]Unknown
Source package: [gnutls28]
Details (4)
- 3.7.9-2+deb12u7 · amd64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · amd64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
[libgnutls-openssl27]Unknown
Source package: [gnutls28]
Details (4)
- 3.7.9-2+deb12u7 · amd64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · amd64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
[libgnutlsxx30]Unknown
Source package: [gnutls28]
Details (4)
- 3.7.9-2+deb12u7 · amd64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · amd64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm
- 3.7.9-2+deb12u7 · arm64 · bookworm-security
  Fixed · Fixed: 3.7.3-2
  nvd · gnutls28 · debian · bookworm

Observed: Oct 23, 2026, 6:03:08 PM UTC

References

[CERT-Bund public advisories] · [CISA cybersecurity advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [SUSE security advisories and VEX]