---
id: CVE-2021-27212
title: >-
  In OpenLDAP through 2.4.57 and 2.5.x through 2.5.1alpha, an assertion failure
  in slapd can occur in the issuerAndThisUpdateCheck function via a crafted
  packet, resulting in a denial of service (daemon exit) via a short timestamp
summary: >-
  In OpenLDAP through 2.4.57 and 2.5.x through 2.5.1alpha, an assertion failure
  in slapd can occur in the issuerAndThisUpdateCheck function via a crafted
  packet, resulting in a denial of service (daemon exit) via a short timestamp.
  This is…
severity: high
cvss: 7.5
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'
cwe:
  - CWE-617
vendor: openldap
product: openldap
affected:
  - openldap <= 2.4.57
  - openldap = 2.5.0
  - openldap = 2.5.1
  - debian_linux = 9.0
  - debian_linux = 10.0
published: '2021-02-14'
updated: '2026-10-14'
sourceUpdated: '2026-10-14T12:17:09.847'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2021-27212'
references:
  - url: 'https://bugs.openldap.org/show_bug.cgi?id=9454'
    label: cve@mitre.org
  - url: >-
      https://git.openldap.org/openldap/openldap/-/commit/3539fc33212b528c56b716584f2c2994af7c30b0
    label: cve@mitre.org
  - url: >-
      https://git.openldap.org/openldap/openldap/-/commit/9badb73425a67768c09bcaed1a9c26c684af6c30
    label: cve@mitre.org
  - url: >-
      https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
    label: cve@mitre.org
  - url: >-
      https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
    label: cve@mitre.org
  - url: 'https://lists.debian.org/debian-lts-announce/2021/02/msg00035.html'
    label: cve@mitre.org
  - url: 'https://security.netapp.com/advisory/ntap-20210319-0005/'
    label: cve@mitre.org
  - url: 'https://www.debian.org/security/2021/dsa-4860'
    label: cve@mitre.org
  - url: 'https://bugs.openldap.org/show_bug.cgi?id=9454'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://git.openldap.org/openldap/openldap/-/commit/3539fc33212b528c56b716584f2c2994af7c30b0
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://git.openldap.org/openldap/openldap/-/commit/9badb73425a67768c09bcaed1a9c26c684af6c30
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: >-
      https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://lists.debian.org/debian-lts-announce/2021/02/msg00035.html'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://security.netapp.com/advisory/ntap-20210319-0005/'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://www.debian.org/security/2021/dsa-4860'
    label: af854a3a-2127-422b-91ae-364da2661108
  - url: 'https://cert-portal.siemens.com/productcert/html/ssa-398330.html'
    label: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e
tags:
  - nvd
epss: 0.63321
epssPercentile: 0.99195
ingestedAt: '2026-10-14T12:29:10.814Z'
---

## Overview

In OpenLDAP through 2.4.57 and 2.5.x through 2.5.1alpha, an assertion failure in slapd can occur in the issuerAndThisUpdateCheck function via a crafted packet, resulting in a denial of service (daemon exit) via a short timestamp. This is related to schema_init.c and checkTime.

## Affected

- `openldap <= 2.4.57`
- `openldap = 2.5.0`
- `openldap = 2.5.1`
- `debian_linux = 9.0`
- `debian_linux = 10.0`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.