CVE-2021-27212

Exp

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.

Published: 2021-02-13 Last update: 2026-06-16 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-27212 is rated High Exploit Risk (84.7/100): CVSS High severity, with high exploitation likelihood (EPSS 64.15%, 99th percentile). 1 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +39.03% over the last day, indicating growing attacker interest. Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-27212

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-27212

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 25.11% 64.15% +39.03%
2 2026-05-05 22.80% 25.11% +2.32%
3 2026-05-03 — 22.80% —

Full EPSS history (36 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-27212

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
7.5 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 3.6 [email protected]
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-27212

OS Trackers for CVE-2021-27212

vendor priority summary link
alpine high CVE-2021-27212: 1 source package rows (openldap); 40 state rows across 10 repos (3.10-main, 3.11-main, 3.12-main, 3.17-main, 3.18-main, 3.19-main, 3.20-main, 3.21-main, 3.22-main, edge-main); fixed 8, open 32. https://security.alpinelinux.org/vuln/CVE-2021-27212
debian not yet assigned CVE-2021-27212 not yet assigned priority: Debian including 1 source packages (openldap), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-27212
redhat medium — https://access.redhat.com/security/cve/CVE-2021-27212
suse high CVE-2021-27212 severity important: SUSE including 443 source package names (0.1.0:libldap-2_4-2-2.4.46-9.48.1, 0.1.0:libldap-data-2.4.46-9.48.1, …), 814 product×package rows across 144 product lines (Container bci/dotnet-aspnet, Container bci/dotnet-runtime, … (144 product lines)): Fixed 679, Known Affected 135. https://www.suse.com/security/cve/CVE-2021-27212/
ubuntu medium CVE-2021-27212 medium priority: Ubuntu including 1 source packages (openldap), 15 status rows across 15 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, trusty, upstream, xenial): released 15. https://ubuntu.com/security/CVE-2021-27212

Affected software / configurations for CVE-2021-27212

Vendor Product Version Raw CPE
openldap openldap <= 2.4.57 cpe:2.3:a:openldap:openldap:*:*:*:*:*:*:*:*
openldap openldap 2.5.0 cpe:2.3:a:openldap:openldap:2.5.0:alpha:*:*:*:*:*:*
openldap openldap 2.5.1 cpe:2.3:a:openldap:openldap:2.5.1:alpha:*:*:*:*:*:*
debian debian_linux 9.0 cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*

References for CVE-2021-27212

URL Tags
https://bugs.openldap.org/show_bug.cgi?id=9454 Exploit Issue Tracking Vendor Advisory
https://git.openldap.org/openldap/openldap/-/commit/3539fc33212b528c56b716584f2c2994af7c30b0 Patch Vendor Advisory
https://git.openldap.org/openldap/openldap/-/commit/9badb73425a67768c09bcaed1a9c26c684af6c30 Patch Vendor Advisory
https://lists.apache.org/thread.html/r58af02e294bd07f487e2c64ffc0a29b837db5600e33b6e698b9d696b%40%3Cissues.bookkeeper.apache.org%3E
https://lists.apache.org/thread.html/rf4c02775860db415b4955778a131c2795223f61cb8c6a450893651e4%40%3Cissues.bookkeeper.apache.org%3E
https://lists.debian.org/debian-lts-announce/2021/02/msg00035.html Mailing List Third Party Advisory
https://security.netapp.com/advisory/ntap-20210319-0005/ Third Party Advisory
https://www.debian.org/security/2021/dsa-4860 Third Party Advisory
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