CVE-2021-27212
HighIn 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.
Published Feb 14, 2021 · Updated Oct 16, 2026 · Also known as ALPINE-CVE-2021-27212, BIT-openldap-2021-27212, DEBIAN-CVE-2021-27212, DLA-2574-1, DSA-4860-1, JLSEC-2026-173, UBUNTU-CVE-2021-27212, USN-4744-1, USN-7713-1
Key Facts
Patch immediately- CVE-2021-27212 is a high-severity vulnerability (CVSS 7.5 v3.1) affecting Openldap, Debian Linux, rootio-openldap and 22 more products.
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- EPSS estimates a 66% probability of exploitation in the next 30 days.
- Fixed versions are available, including compat-libldap-2_3-0 2.3.37-2.74.26.1, compat-libldap-2_3-0 2.3.37-39.1, ldap-utils 2.4.31-1+nmu2ubuntu8.5+esm8.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (30-day exploit likelihood)
66%
Higher than 99.2% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
None known
Get the full CVE-2021-27212 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
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 Products
398 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| OpenldapOpenldap | 2.5.0-alpha, 2.5.1-alpha | 2.4.57 |
| Debian LinuxDebian | 10.0, 9.0 | n/a |
| rootio-openldaprootio | See advisory | 2.4.57+dfsg-2 |
| ldap-utilsubuntu | See advisory | 2.4.31-1+nmu2ubuntu8.5+esm8 |
| libldap-2.4-2ubuntu | See advisory | 2.4.31-1+nmu2ubuntu8.5+esm8 |
Patched Releases
compat-libldap-2_3-0
2.3.37-2.74.26.1, 2.3.37-39.1
ldap-utils
2.4.31-1+nmu2ubuntu8.5+esm8
libldap-2_4-2
2.4.26-0.74.26.1, 2.4.41-18.83.1, 2.4.46-9.48.1, 2.4.46-lp152.14.18.1
libldap-2_4-2-32bit
2.4.26-0.74.26.1, 2.4.41-18.83.1, 2.4.46-9.48.1, 2.4.46-lp152.14.18.1
libldap-2.4-2
2.4.31-1+nmu2ubuntu8.5+esm8
libldap-data
2.4.46-9.48.1, 2.4.46-lp152.14.18.1
libldap-openssl1-2_4-2
2.4.26-0.74.26.1
libldap-openssl1-2_4-2-32bit
2.4.26-0.74.26.1
libldap-openssl1-2_4-2-x86
2.4.26-0.74.26.1
libldap2-dev
2.4.31-1+nmu2ubuntu8.5+esm8
Openldap
2.4.31-1+nmu2ubuntu8.5+esm8, 2.4.40-16.36.amzn1, 2.4.42+dfsg-2ubuntu3.13, 2.4.44-25.amzn2.0.5, 2.4.44+dfsg-5+deb9u8, 2.4.45+dfsg-1ubuntu1.10, 2.4.47+dfsg-3+deb10u6, 2.4.49+dfsg-2ubuntu1.7, 2.4.50-r2, 2.4.57-1.ph4, 2.4.57-2, 2.4.57-2.ph1, 2.4.57-2.ph2, 2.4.57-2.ph3, 2.4.57-5, 2.4.57-6.amzn2023.0.4, 2.4.57-r1, 2.4.57+dfsg-2, 2.4.58, 2.4.58-1, <=2.4.57
openldap-clients
2.4.40-16.36.amzn1, 2.4.44-25.amzn2.0.5, 2.4.57-6.amzn2023.0.4
openldap-compat
2.4.57-6.amzn2023.0.4
openldap-devel
2.4.40-16.36.amzn1, 2.4.44-25.amzn2.0.5, 2.4.57-6.amzn2023.0.4
openldap-servers
2.4.40-16.36.amzn1, 2.4.44-25.amzn2.0.5, 2.4.57-6.amzn2023.0.4
openldap-servers-sql
2.4.40-16.36.amzn1, 2.4.44-25.amzn2.0.5
openldap2
2.4.26-0.74.26.1, 2.4.41-18.83.1, 2.4.41-39.1, 2.4.46-9.48.1, 2.4.46-lp152.14.18.1
openldap2-back-meta
2.4.26-0.74.26.1, 2.4.41-18.83.1, 2.4.46-9.48.1, 2.4.46-lp152.14.18.1
openldap2-back-perl
2.4.41-18.83.1, 2.4.46-9.48.1, 2.4.46-lp152.14.18.1
openldap2-back-sock
2.4.46-lp152.14.18.1
openldap2-back-sql
2.4.46-lp152.14.18.1
openldap2-client
2.4.26-0.74.26.1, 2.4.41-18.83.1, 2.4.46-9.48.1, 2.4.46-lp152.14.18.1
openldap2-client-openssl1
2.4.26-0.74.26.1
openldap2-contrib
2.4.46-lp152.14.18.1
openldap2-devel
2.4.41-18.83.1, 2.4.46-9.48.1, 2.4.46-lp152.14.18.1
Timeline
Publicly disclosed
Feb 14, 2021
Last updated
Oct 16, 2026
Weakness Type
- CWE-400 Uncontrolled Resource Consumption
- CWE-617 Reachable Assertion
References
- advisoryhttps://bugzilla.suse.com/1182279
- advisoryhttps://bugzilla.suse.com/1182408
- advisoryhttps://bugzilla.suse.com/1182411
- advisoryhttps://bugzilla.suse.com/1182412
- advisoryhttps://bugzilla.suse.com/1182413
FAQ
Common Questions.
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.
Affected: Openldap versions 2.5.0-alpha, 2.5.1-alpha; Debian Linux versions 10.0, 9.0; rootio-openldap, among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including compat-libldap-2_3-0 2.3.37-2.74.26.1, compat-libldap-2_3-0 2.3.37-39.1, ldap-utils 2.4.31-1+nmu2ubuntu8.5+esm8.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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