Every CVE Search/ Get API key

CVE-2021-4209

A NULL pointer dereference flaw was found in GnuTLS. As Nettle's hash update functions internally...

6.5 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

1.91%Up 1.0 points since Aug 25, 2022
90%50%10%1%

What each source reports

NVD Score used 6.5

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.

Record
CVE-2021-4209
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-476
Updated
2026-11-02
CVE List No score

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.

Record
CVE-2021-4209
Weakness
CWE-476
Updated
2026-11-02
EUVDEUVD-2021-34067 No score

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.

Record
EUVD-2021-34067
Updated
2026-11-02
GitHub AdvisoriesGHSA-xj78-h3gx-cm6v 6.5

A NULL pointer dereference flaw was found in GnuTLS. As Nettle's hash update functions internally...

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.

Record
GHSA-xj78-h3gx-cm6v
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-476
Updated
2026-11-02
OSV 6.5

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.

Record
CVE-2021-4209
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2021-4209 6.5

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.

Record
DEBIAN-CVE-2021-4209
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 11 moreShow less
OSVJLSEC-2026-522 6.5

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.

Record
JLSEC-2026-522
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVOESA-2022-1889 6.5

gnutls security update

GnuTLS is a secure communications library implementing the SSL, TLS and DTLS protocols and technologies around them. It provides a simple C language application programming interface (API) to access the secure communications protocols as well as APIs to parse and write X.509, PKCS #12, and other required structures.The project strives to provide a secure communications back-end, simple to use and integrated with the rest of the base Linux libraries. A back-end designed to work and be secure out of the box, keeping the complexity of TLS and PKI out of application code.

Security Fix(es):

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.(CVE-2021-4209)

Record
OESA-2022-1889
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2021-4209 6.5

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.

Record
UBUNTU-CVE-2021-4209
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVMGASA-2022-0098 No score

Updated gnutls packages fix security vulnerability

Null pointer dereference in MD_UPDATE. (CVE-2021-4209)

Record
MGASA-2022-0098
Updated
2026-11-02
OSVopenSUSE-SU-2022:0717-1 No score

Security update for gnutls

This update for gnutls fixes the following issues:

  • CVE-2021-4209: Fixed null pointer dereference in MD_UPDATE (bsc#1196167).
Record
openSUSE-SU-2022:0717-1
Updated
2026-11-02
OSVSUSE-SU-2022:0677-1 No score

Security update for gnutls

This update for gnutls fixes the following issues:

  • CVE-2021-4209: Fixed null pointer dereference in MD_UPDATE (bsc#1196167).
Record
SUSE-SU-2022:0677-1
Updated
2026-11-02
OSVSUSE-SU-2022:0678-1 No score

Security update for gnutls

This update for gnutls fixes the following issues:

  • CVE-2021-4209: Fixed null pointer dereference in MD_UPDATE (bsc#1196167).
Record
SUSE-SU-2022:0678-1
Updated
2026-11-02
OSVSUSE-SU-2022:0717-1 No score

Security update for gnutls

This update for gnutls fixes the following issues:

  • CVE-2021-4209: Fixed null pointer dereference in MD_UPDATE (bsc#1196167).
Record
SUSE-SU-2022:0717-1
Updated
2026-11-02
OSVSUSE-SU-2022:2830-1 No score

Security update for gnutls

This update for gnutls fixes the following issues:

  • CVE-2022-2509: Fixed a double free issue during PKCS7 verification (bsc#1202020).
  • CVE-2021-4209: Fixed null pointer dereference in MD_UPDATE (bsc#1196167).
Record
SUSE-SU-2022:2830-1
Updated
2026-11-02
OSVUSN-5550-1 No score

gnutls28 vulnerabilities

It was discovered that GnuTLS incorrectly handled certain memory operations. A remote attacker could possibly use this issue to cause GnuTLS to crash, resulting in a denial of service. This issue only affected Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS. (CVE-2021-4209)

It was discovered that GnuTLS incorrectly handled the verification of certain pkcs7 signatures. A remote attacker could use this issue to cause GnuTLS to crash, resulting in a denial of service, or possibly execute arbitrary code. (CVE-2022-2509)

Record
USN-5550-1
Updated
2026-11-02
OSVUSN-5750-1 No score

gnutls28 vulnerability

It was discovered that GnuTLS incorrectly handled certain memory operations. A remote attacker could possibly use this issue to cause GnuTLS to crash, resulting in a denial of service.

Record
USN-5750-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
gnutls28
Debian:12
 before 3.7.3-2
3.7.3-2
gnutls28
Debian:13
 before 3.7.3-2
3.7.3-2
gnutls28
Debian:14
 before 3.7.3-2
3.7.3-2
gnutls28
Debian:10
From an advisory covering 2 CVEs
 before 3.6.7-4+deb10u9, plus listed versions
3.6.7-43.6.7-4+deb10u13.6.7-4+deb10u23.6.7-4+deb10u33.6.7-4+deb10u4
Show 4 moreShow less
3.6.7-4+deb10u53.6.7-4+deb10u63.6.7-4+deb10u73.6.7-4+deb10u8
3.6.7-4+deb10u9
GnuTLS_jll
Julia
 before 3.7.8+0
3.7.8+0
gnutls
Mageia:8
 before 3.6.15-3.2.mga8
3.6.15-3.2.mga8
gnutls
openEuler:20.03-LTS-SP1
 before 3.6.14-9.oe1
3.6.14-9.oe1
gnutls
openEuler:20.03-LTS-SP3
 before 3.6.14-9.oe1
3.6.14-9.oe1
gnutls
openEuler:22.03-LTS
 before 3.7.2-4.oe2203
3.7.2-4.oe2203
gnutls
SUSE:Linux Enterprise Software Development Kit 12 SP5
 before 3.3.27-3.6.1
3.3.27-3.6.1
Show 26 moreShow less
Affected packages
PackageAffectedFixed
gnutls
SUSE:Linux Enterprise Server 12 SP5
 before 3.3.27-3.6.1
3.3.27-3.6.1
gnutls
SUSE:Linux Enterprise Server for SAP Applications 12 SP5
 before 3.3.27-3.6.1
3.3.27-3.6.1
gnutls
SUSE:Linux Enterprise Server 12 SP5
 before 3.4.17-8.11.1
3.4.17-8.11.1
gnutls
SUSE:Linux Enterprise Server for SAP Applications 12 SP5
 before 3.4.17-8.11.1
3.4.17-8.11.1
gnutls
SUSE:Linux Enterprise Module for Basesystem 15 SP3
 before 3.6.7-14.16.1
3.6.7-14.16.1
gnutls
SUSE:Linux Enterprise Real Time 15 SP2
 before 3.6.7-14.16.1
3.6.7-14.16.1
gnutls
SUSE:Linux Enterprise Micro 5.0
 before 3.6.7-14.16.1
3.6.7-14.16.1
gnutls
SUSE:Linux Enterprise Micro 5.1
 before 3.6.7-14.16.1
3.6.7-14.16.1
gnutls
SUSE:Linux Enterprise High Performance Computing 15-ESPOS
From an advisory covering 2 CVEs
 before 3.6.7-150000.6.45.2
3.6.7-150000.6.45.2
gnutls
SUSE:Linux Enterprise High Performance Computing 15-LTSS
From an advisory covering 2 CVEs
 before 3.6.7-150000.6.45.2
3.6.7-150000.6.45.2
gnutls
SUSE:Linux Enterprise High Performance Computing 15 SP1-ESPOS
From an advisory covering 2 CVEs
 before 3.6.7-150000.6.45.2
3.6.7-150000.6.45.2
gnutls
SUSE:Linux Enterprise High Performance Computing 15 SP1-LTSS
From an advisory covering 2 CVEs
 before 3.6.7-150000.6.45.2
3.6.7-150000.6.45.2
gnutls
SUSE:Linux Enterprise Server 15-LTSS
From an advisory covering 2 CVEs
 before 3.6.7-150000.6.45.2
3.6.7-150000.6.45.2
gnutls
SUSE:Linux Enterprise Server 15 SP1-BCL
From an advisory covering 2 CVEs
 before 3.6.7-150000.6.45.2
3.6.7-150000.6.45.2
gnutls
SUSE:Linux Enterprise Server 15 SP1-LTSS
From an advisory covering 2 CVEs
 before 3.6.7-150000.6.45.2
3.6.7-150000.6.45.2
gnutls
SUSE:Linux Enterprise Server for SAP Applications 15
From an advisory covering 2 CVEs
 before 3.6.7-150000.6.45.2
3.6.7-150000.6.45.2
gnutls
SUSE:Linux Enterprise Server for SAP Applications 15 SP1
From an advisory covering 2 CVEs
 before 3.6.7-150000.6.45.2
3.6.7-150000.6.45.2
gnutls
SUSE:Enterprise Storage 6
From an advisory covering 2 CVEs
 before 3.6.7-150000.6.45.2
3.6.7-150000.6.45.2
gnutls26
Ubuntu:Pro:14.04:LTS
 All versions, plus listed versions
2.12.23-1ubuntu42.12.23-1ubuntu52.12.23-12ubuntu12.12.23-12ubuntu22.12.23-12ubuntu2.1
Show 8 moreShow less
2.12.23-12ubuntu2.22.12.23-12ubuntu2.32.12.23-12ubuntu2.42.12.23-12ubuntu2.52.12.23-12ubuntu2.62.12.23-12ubuntu2.72.12.23-12ubuntu2.82.12.23-12ubuntu2.10+esm1
 None known
gnutls28
Ubuntu:Pro:16.04:LTS
 before 3.4.10-4ubuntu1.9+esm1, plus listed versions
3.3.15-5ubuntu23.3.18-1ubuntu13.3.20-1ubuntu13.4.9-2ubuntu13.4.10-4ubuntu1
Show 9 moreShow less
3.4.10-4ubuntu1.13.4.10-4ubuntu1.23.4.10-4ubuntu1.33.4.10-4ubuntu1.43.4.10-4ubuntu1.53.4.10-4ubuntu1.63.4.10-4ubuntu1.73.4.10-4ubuntu1.83.4.10-4ubuntu1.9
3.4.10-4ubuntu1.9+esm1
gnutls28
Ubuntu:18.04:LTS
 before 3.5.18-1ubuntu1.6, plus listed versions
3.5.8-6ubuntu33.5.17-1ubuntu13.5.17-1ubuntu33.5.18-1ubuntu13.5.18-1ubuntu1.1
Show 4 moreShow less
3.5.18-1ubuntu1.23.5.18-1ubuntu1.33.5.18-1ubuntu1.43.5.18-1ubuntu1.5
3.5.18-1ubuntu1.6
gnutls28
Ubuntu:20.04:LTS
 before 3.6.13-2ubuntu1.7, plus listed versions
3.6.9-5ubuntu13.6.9-5ubuntu23.6.10-53.6.11.1-23.6.11.1-2ubuntu2
Show 5 moreShow less
3.6.13-2ubuntu13.6.13-2ubuntu1.13.6.13-2ubuntu1.23.6.13-2ubuntu1.33.6.13-2ubuntu1.6
3.6.13-2ubuntu1.7
gnutls28
Ubuntu:18.04:LTS
From an advisory covering 2 CVEs
 before 3.5.18-1ubuntu1.6, plus listed versions
3.5.8-6ubuntu33.5.17-1ubuntu13.5.17-1ubuntu33.5.18-1ubuntu13.5.18-1ubuntu1.1
Show 4 moreShow less
3.5.18-1ubuntu1.23.5.18-1ubuntu1.33.5.18-1ubuntu1.43.5.18-1ubuntu1.5
3.5.18-1ubuntu1.6
gnutls28
Ubuntu:20.04:LTS
From an advisory covering 2 CVEs
 before 3.6.13-2ubuntu1.7, plus listed versions
3.6.9-5ubuntu13.6.9-5ubuntu23.6.10-53.6.11.1-23.6.11.1-2ubuntu2
Show 5 moreShow less
3.6.13-2ubuntu13.6.13-2ubuntu1.13.6.13-2ubuntu1.23.6.13-2ubuntu1.33.6.13-2ubuntu1.6
3.6.13-2ubuntu1.7
gnutls28
Ubuntu:22.04:LTS
From an advisory covering 2 CVEs
 before 3.7.3-4ubuntu1.1, plus listed versions
3.7.1-5ubuntu13.7.2-2ubuntu13.7.2-4ubuntu13.7.2-5ubuntu13.7.3-4ubuntu1
3.7.3-4ubuntu1.1
gnutls
openSUSE:Leap 15.3
 before 3.6.7-14.16.1
3.6.7-14.16.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2021-4209 is a medium vulnerability (CVSS 6.5) in Gnu Gnutls, published February 22, 2022. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.91%, the 79th percentile. Fixed in gnutls28 3.7.3-2.

References

Show 22 moreShow less
Pages All vulnerabilities Browse Docs Sources Guide Get API key
MoveEnter Open