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NVD / CVE Program· CNA mitre

CVE-2021-27212: 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…

HighCVSS 7.5 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Plan (action score 50/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 66.1% (FIRST EPSS); higher than 99.2% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: openldap (Alpine:v3.12) 2.4.50-r2; openldap (Alpine:v3.13) 2.4.57-r1; openldap (Debian:10) 2.4.47+dfsg-3+deb10u6.

Add it to your regular patch cycle. Upgrade to openldap (Alpine:v3.12) 2.4.50-r2; openldap (Alpine:v3.13) 2.4.57-r1; openldap (Debian:10) 2.4.47+dfsg-3+deb10u6 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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
Feb 14, 2021
Updated
Oct 14, 2026
EPSS
66.1% · 99th percentile

Report tools

JSON

Action score

50

Plan

Add it to your regular patch cycle.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
20 / 30 · 66.1%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-27212

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
openldapopenldap
debiandebian linux

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux10.0
  • debian debian linux9.0
  • openldap openldapup to 2.4.57 inclusive
  • openldap openldap2.5.0
  • openldap openldap2.5.1

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.12openldapbefore 2.4.50-r22.4.50-r2
Alpine:v3.13openldapbefore 2.4.57-r12.4.57-r1
Debian:10openldapbefore 2.4.47+dfsg-3+deb10u62.4.47+dfsg-3+deb10u6
Debian:12openldapbefore 2.4.57+dfsg-22.4.57+dfsg-2
Debian:9openldapbefore 2.4.44+dfsg-5+deb9u82.4.44+dfsg-5+deb9u8
openSUSE:Leap 15.2openldap2before 2.4.46-lp152.14.18.12.4.46-lp152.14.18.1
SUSE:HPE Helion OpenStack 8openldap2before 2.4.41-18.83.12.4.41-18.83.1
SUSE:Linux Enterprise Module for Basesystem 15 SP2openldap2before 2.4.46-9.48.12.4.46-9.48.1
SUSE:Linux Enterprise Module for Legacy 12openldap2before 2.4.41-39.12.4.41-39.1
SUSE:Linux Enterprise Point of Sale 11 SP3openldap2before 2.4.26-0.74.26.12.4.26-0.74.26.1
SUSE:Linux Enterprise Point of Sale 11 SP3openldap2-clientbefore 2.4.26-0.74.26.12.4.26-0.74.26.1
SUSE:Linux Enterprise Server 11-SECURITYopenldap2-client-openssl1before 2.4.26-0.74.26.12.4.26-0.74.26.1

Same product

openldap: all records

Other highest-scoring records for the same primary product.

  • CVE-2022-29155In OpenLDAP 2.x before 2.5.12 and 2.6.x before 2.6.2, a SQL injection vulnerability exists in the experimental back-sql backend to slapd…
    58Plan
  • CVE-2020-36228An integer underflow was discovered in OpenLDAP before 2.4.57 leading to a slapd crash in the Certificate List Exact Assertion processing…
    55Plan
  • CVE-2020-36221An integer underflow was discovered in OpenLDAP before 2.4.57 leading to slapd crashes in the Certificate Exact Assertion processing…
    55Plan

Published before and after this one in the same product

  • ← EarlierCVE-2020-36229Jan 26, 2021 · A flaw was discovered in ldap_X509dn2bv in OpenLDAP before 2.4.57 leading to a slapd crash in the X.509 DN parsing in ad_keystring…
    31Monitor
  • ← EarlierCVE-2020-36230Jan 26, 2021 · A flaw was discovered in OpenLDAP before 2.4.57 leading in an assertion failure in slapd in the X.509 DN parsing in decode.c…
    34Monitor
  • Later →CVE-2020-25709May 18, 2021 · A flaw was found in OpenLDAP.
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:openldap2.4.50-r2 · Alpine:v3.12Package registry (OSV)
debian:openldap2.4.57+dfsg-2 · Debian:12Package registry (OSV)
opensuse:openldap22.4.46-lp152.14.18.1 · openSUSE:Leap 15.2Package registry (OSV)
suse:openldap22.4.41-39.1 · SUSE:Linux Enterprise Module for Legacy 12Package registry (OSV)
suse:openldap2-client2.4.26-0.74.26.1 · SUSE:Linux Enterprise Point of Sale 11 SP3Package registry (OSV)
suse:openldap2-client-openssl12.4.26-0.74.26.1 · SUSE:Linux Enterprise Server 11-SECURITYPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Not on record for this CVE: researcher credit · variant or chain candidate · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-617 · Reachable Assertion

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records