# CVE-2020-36221: libldap2: An integer underflow was discovered in OpenLDAP before 2.4.57 leading toslapd crashes in the Certificate Exact Assert...

CVE-2020-36221 is fixed in 7 products on 1 platform, first by ldap-utils 2.4.45+dfsg-1ubuntu1.9, released January 26, 2021. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2020-36221
- Priority: Routine
- CVSS: n/a (Medium)
- EPSS: 0.8499
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jan 26, 2021

## Description

An integer underflow was discovered in OpenLDAP before 2.4.57 leading toslapd crashes in the Certificate Exact Assertion processing, resulting indenial of service (schema_init.c serialNumberAndIssuerCheck).

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | ldap-utils Ubuntu 18.04.6 LTS (bionic) | 2.4.45+dfsg-1ubuntu1.9 | [ldap-utils 2.4.45+dfsg-1ubuntu1.9](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-ldap-utils-2.4.45-dfsg-1ubuntu1.9.md) | Jan 26, 2021 |
| Linux | ldap-utils Ubuntu 20.04 LTS (focal) | 2.4.49+dfsg-2ubuntu1.6 | [ldap-utils 2.4.49+dfsg-2ubuntu1.6](https://patchblox.com/security/data/fix/linux/ubuntu-focal-ldap-utils-2.4.49-dfsg-2ubuntu1.6.md) | Jan 26, 2021 |
| Linux | ldap-utils Ubuntu 24.10 (oracular) | 2.4.57+dfsg-2ubuntu1 | [ldap-utils 2.4.57+dfsg-2ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-ldap-utils-2.4.57-dfsg-2ubuntu1.md) | Jan 16, 2026 |
| Linux | ldap-utils Ubuntu 25.04 (plucky) | 2.4.57+dfsg-2ubuntu1 | [ldap-utils 2.4.57+dfsg-2ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-ldap-utils-2.4.57-dfsg-2ubuntu1.md) | Jan 16, 2026 |
| Linux | libldap-2.4-2 Ubuntu 18.04.6 LTS (bionic) | 2.4.45+dfsg-1ubuntu1.9 | [libldap-2.4-2 2.4.45+dfsg-1ubuntu1.9](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libldap-2.4-2-2.4.45-dfsg-1ubuntu1.9.md) | Jan 26, 2021 |
| Linux | libldap-2.4-2 Ubuntu 20.04 LTS (focal) | 2.4.49+dfsg-2ubuntu1.6 | [libldap-2.4-2 2.4.49+dfsg-2ubuntu1.6](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libldap-2.4-2-2.4.49-dfsg-2ubuntu1.6.md) | Jan 26, 2021 |
| Linux | libldap-common Ubuntu 18.04.6 LTS (bionic) | 2.4.45+dfsg-1ubuntu1.9 | [libldap-common 2.4.45+dfsg-1ubuntu1.9](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libldap-common-2.4.45-dfsg-1ubuntu1.9.md) | Jan 26, 2021 |
| Linux | libldap-common Ubuntu 20.04 LTS (focal) | 2.4.49+dfsg-2ubuntu1.6 | [libldap-common 2.4.49+dfsg-2ubuntu1.6](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libldap-common-2.4.49-dfsg-2ubuntu1.6.md) | Jan 26, 2021 |
| Linux | libldap-common Ubuntu 24.10 (oracular) | 2.4.57+dfsg-2ubuntu1 | [libldap-common 2.4.57+dfsg-2ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-libldap-common-2.4.57-dfsg-2ubuntu1.md) | Jan 16, 2026 |
| Linux | libldap-common Ubuntu 25.04 (plucky) | 2.4.57+dfsg-2ubuntu1 | [libldap-common 2.4.57+dfsg-2ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-libldap-common-2.4.57-dfsg-2ubuntu1.md) | Jan 16, 2026 |
| Linux | libldap2 Ubuntu 24.10 (oracular) | 2.4.57+dfsg-2ubuntu1 | [libldap2 2.4.57+dfsg-2ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-libldap2-2.4.57-dfsg-2ubuntu1.md) | Jan 16, 2026 |
| Linux | libldap2 Ubuntu 25.04 (plucky) | 2.4.57+dfsg-2ubuntu1 | [libldap2 2.4.57+dfsg-2ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-libldap2-2.4.57-dfsg-2ubuntu1.md) | Jan 16, 2026 |
| Linux | slapd Ubuntu 18.04.6 LTS (bionic) | 2.4.45+dfsg-1ubuntu1.9 | [slapd 2.4.45+dfsg-1ubuntu1.9](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-slapd-2.4.45-dfsg-1ubuntu1.9.md) | Jan 26, 2021 |
| Linux | slapd Ubuntu 20.04 LTS (focal) | 2.4.49+dfsg-2ubuntu1.6 | [slapd 2.4.49+dfsg-2ubuntu1.6](https://patchblox.com/security/data/fix/linux/ubuntu-focal-slapd-2.4.49-dfsg-2ubuntu1.6.md) | Jan 26, 2021 |
| Linux | slapd Ubuntu 24.10 (oracular) | 2.4.57+dfsg-2ubuntu1 | [slapd 2.4.57+dfsg-2ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-slapd-2.4.57-dfsg-2ubuntu1.md) | Jan 16, 2026 |
| Linux | slapd Ubuntu 25.04 (plucky) | 2.4.57+dfsg-2ubuntu1 | [slapd 2.4.57+dfsg-2ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-slapd-2.4.57-dfsg-2ubuntu1.md) | Jan 16, 2026 |
| Linux | slapd-contrib Ubuntu 20.04 LTS (focal) | 2.4.49+dfsg-2ubuntu1.6 | [slapd-contrib 2.4.49+dfsg-2ubuntu1.6](https://patchblox.com/security/data/fix/linux/ubuntu-focal-slapd-contrib-2.4.49-dfsg-2ubuntu1.6.md) | Jan 26, 2021 |
| Linux | slapd-contrib Ubuntu 24.10 (oracular) | 2.4.57+dfsg-2ubuntu1 | [slapd-contrib 2.4.57+dfsg-2ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-slapd-contrib-2.4.57-dfsg-2ubuntu1.md) | Jan 16, 2026 |
| Linux | slapd-contrib Ubuntu 25.04 (plucky) | 2.4.57+dfsg-2ubuntu1 | [slapd-contrib 2.4.57+dfsg-2ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-slapd-contrib-2.4.57-dfsg-2ubuntu1.md) | Jan 16, 2026 |
| Linux | slapd-smbk5pwd Ubuntu 18.04.6 LTS (bionic) | 2.4.45+dfsg-1ubuntu1.9 | [slapd-smbk5pwd 2.4.45+dfsg-1ubuntu1.9](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-slapd-smbk5pwd-2.4.45-dfsg-1ubuntu1.9.md) | Jan 26, 2021 |
| Linux | slapd-smbk5pwd Ubuntu 20.04 LTS (focal) | 2.4.49+dfsg-2ubuntu1.6 | [slapd-smbk5pwd 2.4.49+dfsg-2ubuntu1.6](https://patchblox.com/security/data/fix/linux/ubuntu-focal-slapd-smbk5pwd-2.4.49-dfsg-2ubuntu1.6.md) | Jan 26, 2021 |
| Linux | slapd-smbk5pwd Ubuntu 24.10 (oracular) | 2.4.57+dfsg-2ubuntu1 | [slapd-smbk5pwd 2.4.57+dfsg-2ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-slapd-smbk5pwd-2.4.57-dfsg-2ubuntu1.md) | Jan 16, 2026 |

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