# CVE-2021-37750: Null dereference in n/a > A NULL pointer dereference in the MIT Kerberos KDC allows remote attackers to cause a denial of service via a crafted FAST inner body. - **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`) - **Exploited in the wild:** Not known - **Login needed:** Any signed-in user - **Attackable:** Over the internet - **Victim action needed:** Not needed - **Fix available:** Yes - **Published:** 23 Aug 2021 - **Updated:** 14 Oct 2026 - **Also known as:** ALPINE-CVE-2021-37750, AZL-6608, CLEANSTART-2024-TG46953, DEBIAN-CVE-2021-37750, GHSA-p36j-vmfc-m4v5, OESA-2021-1329, RHSA-2021:4788, SUSE-SU-2021:3454-1, SUSE-SU-2021:3454-2, SUSE-SU-2024:1702-1, UBUNTU-CVE-2021-37750, openSUSE-SU-2021:1411-1, openSUSE-SU-2021:3454-1 ## What is CVE-2021-37750? CVE-2021-37750 is a medium-severity vulnerability in Debian Debian Linux, published on 23 Aug 2021. Any signed-in user can exploit it over the network, with no action from the victim. ### Official description The Key Distribution Center (KDC) in MIT Kerberos 5 (aka krb5) before 1.18.5 and 1.19.x before 1.19.3 has a NULL pointer dereference in kdc/do_tgs_req.c via a FAST inner body that lacks a server field. Weakness: CWE-476 (NULL Pointer Dereference) ## Which versions are affected by CVE-2021-37750? It affects 5 products. | Package | Ecosystem | Affected | Fixed in | | --- | --- | --- | --- | | `krb5` | Red Hat:enterprise_linux:7::client | All versions | 0:1.15.1-51.el7_9 | | `krb5-debuginfo` | Red Hat:enterprise_linux:7::client | All versions | 0:1.15.1-51.el7_9 | | `krb5-devel` | Red Hat:enterprise_linux:7::client | All versions | 0:1.15.1-51.el7_9 | | `krb5-libs` | Red Hat:enterprise_linux:7::client | All versions | 0:1.15.1-51.el7_9 | | `krb5-pkinit` | Red Hat:enterprise_linux:7::client | All versions | 0:1.15.1-51.el7_9 | | `krb5-server` | Red Hat:enterprise_linux:7::client | All versions | 0:1.15.1-51.el7_9 | | `krb5-server-ldap` | Red Hat:enterprise_linux:7::client | All versions | 0:1.15.1-51.el7_9 | | `krb5-workstation` | Red Hat:enterprise_linux:7::client | All versions | 0:1.15.1-51.el7_9 | | `libkadm5` | Red Hat:enterprise_linux:7::client | All versions | 0:1.15.1-51.el7_9 | | `krb5-debuginfo` | Red Hat:enterprise_linux:7::computenode | All versions | 0:1.15.1-51.el7_9 | | `krb5-devel` | Red Hat:enterprise_linux:7::computenode | All versions | 0:1.15.1-51.el7_9 | | `krb5-server` | Red Hat:enterprise_linux:7::computenode | All versions | 0:1.15.1-51.el7_9 | | `krb5-server-ldap` | Red Hat:enterprise_linux:7::computenode | All versions | 0:1.15.1-51.el7_9 | | `krb5` | Red Hat:enterprise_linux:7::server | All versions | 0:1.15.1-51.el7_9 | | `krb5-debuginfo` | Red Hat:enterprise_linux:7::server | All versions | 0:1.15.1-51.el7_9 | | `krb5-devel` | Red Hat:enterprise_linux:7::server | All versions | 0:1.15.1-51.el7_9 | | `krb5-libs` | Red Hat:enterprise_linux:7::server | All versions | 0:1.15.1-51.el7_9 | | `krb5-pkinit` | Red Hat:enterprise_linux:7::server | All versions | 0:1.15.1-51.el7_9 | | `krb5-server` | Red Hat:enterprise_linux:7::server | All versions | 0:1.15.1-51.el7_9 | | `krb5-server-ldap` | Red Hat:enterprise_linux:7::server | All versions | 0:1.15.1-51.el7_9 | | `krb5-workstation` | Red Hat:enterprise_linux:7::server | All versions | 0:1.15.1-51.el7_9 | | `libkadm5` | Red Hat:enterprise_linux:7::server | All versions | 0:1.15.1-51.el7_9 | | `krb5` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.15.1-51.el7_9 | | `krb5-debuginfo` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.15.1-51.el7_9 | | `krb5-devel` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.15.1-51.el7_9 | | `krb5-libs` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.15.1-51.el7_9 | | `krb5-pkinit` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.15.1-51.el7_9 | | `krb5-server` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.15.1-51.el7_9 | | `krb5-server-ldap` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.15.1-51.el7_9 | | `krb5-workstation` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.15.1-51.el7_9 | | `libkadm5` | Red Hat:enterprise_linux:7::workstation | All versions | 0:1.15.1-51.el7_9 | | `krb5` | SUSE:Linux Enterprise Micro 5.0 | All versions | 1.16.3-3.24.1 | | `krb5` | SUSE:Linux Enterprise Micro 5.1 | All versions | 1.16.3-3.24.1 | | `krb5` | SUSE:Linux Enterprise Module for Basesystem 15 SP2 | All versions | 1.16.3-3.24.1 | | `krb5` | SUSE:Linux Enterprise Module for Basesystem 15 SP3 | All versions | 1.16.3-3.24.1 | | `krb5` | SUSE:Linux Enterprise Module for Server Applications 15 SP2 | All versions | 1.16.3-3.24.1 | | `krb5` | SUSE:Linux Enterprise Module for Server Applications 15 SP3 | All versions | 1.16.3-3.24.1 | | `krb5` | SUSE:Linux Enterprise Server 12 SP5 | All versions | 1.16.3-46.12.1 | | `krb5` | SUSE:Linux Enterprise Server for SAP Applications 12 SP5 | All versions | 1.16.3-46.12.1 | | `krb5` | SUSE:Linux Enterprise Software Development Kit 12 SP5 | All versions | 1.16.3-46.12.1 | Products: Debian Debian Linux, Fedoraproject Fedora, Mit Kerberos 5, Oracle Communications Cloud Native Core Network Slice Selection Function, Starwindsoftware Starwind Virtual San. ## How do I fix CVE-2021-37750? Upgrade to a fixed version. ## Is CVE-2021-37750 being exploited? There is no known exploitation of CVE-2021-37750 in the wild and no public exploit code. ## Other vulnerabilities in Debian Debian Linux - [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild) - [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild) - [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild) - [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild) - [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild) ## Fix prompt for AI coding agents ```text Check this codebase for CVE-2021-37750 and fix it if it is affected. What it is: CVE-2021-37750 is a medium-severity vulnerability in Debian Debian Linux, published on 23 Aug 2021. Any signed-in user can exploit it over the network, with no action from the victim. Exploitation: There is no known exploitation of CVE-2021-37750 in the wild and no public exploit code. Affected product: Debian Debian Linux. No package-level version data is available, so check the vendor advisory linked from the reference page. Task: 1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies. 2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it. 3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead. 4. Run the tests and summarise what changed and why. 5. If nothing in the project is affected, say so and change nothing. Reference: https://insights.sbomify.com/CVE-2021-37750/ (Markdown: https://insights.sbomify.com/CVE-2021-37750/index.md) ``` ## Sources - CVE record: https://www.cve.org/CVERecord?id=CVE-2021-37750 - NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-37750 - OSV: https://osv.dev/vulnerability/CVE-2021-37750 --- From sbomify Insights: https://insights.sbomify.com/CVE-2021-37750/ Summaries are generated and may contain mistakes; the official description above is the record.