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CVE-2020-12243: In filter.c in slapd in OpenLDAP before 2.4.50, LDAP search filters with nested boolean expressions can result

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This week
HIGH 7.5REMOTEWATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2020-12243 is a high-severity flaw (CVSS 7.5) affecting openldap, debian linux, leap. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In filter.c in slapd in OpenLDAP before 2.4.50, LDAP search filters with nested boolean expressions can result in denial of service (daemon crash).

Why this priority

  • High severity
  • EPSS top 8%: very likely to be exploited
  • Public exploit reference
  • Remotely exploitable, no login, no user action
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score7.5 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance4.7% (top 8%)
CISA exploited listNo
WeaknessCWE-674
Published2020-04-28
Last modified2026-10-14
Publisher (CNA): MITRE · Vendor: canonical · debian · netapp · openldap · opensuse

Share: LinkedIn · X · Reddit

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

openldap openldap UPGRADE
Affected: < 2.4.50
Fixed in: 2.4.50
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy openldap || rpm -q openldap || openldap --version
2. UPGRADE to 2.4.50 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade openldap
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade openldap
Note
Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.
debian debian linux MITIGATE
Affected: 8.0 · 9.0 · 10.0
Fixed in: no fixed release known
Safe to downgrade to: a release before 8.0
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
opensuse leap MITIGATE
Affected: 15.1
Fixed in: no fixed release known
Safe to downgrade to: a release before 15.1
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
canonical ubuntu linux MITIGATE
Affected: 12.04 · 14.04 · 16.04 · 18.04 · 19.10 · 20.04
Fixed in: no fixed release known
Safe to downgrade to: a release before 12.04
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
netapp cloud backup MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy cloud-backup || rpm -q cloud-backup || cloud-backup --version
No fixed or unaffected release known
Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.
netapp steelstore cloud integrated storage MITIGATE
Affected: all versions
Fixed in: no fixed release known
Safe to downgrade to: no unaffected older release
1. Check installed version
apt-cache policy steelstore-cloud-integrated-storage || rpm -q steelstore-cloud-integrated-storage || steelstore-cloud-integrated-storage --version
No fixed or unaffected release known
Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-12243?

openldap: upgrade to 2.4.50; debian linux: mitigate or apply the listed mitigation; leap: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-12243 being exploited?

CVE-2020-12243 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-12243 affect?

CVE-2020-12243 affects openldap, debian linux, leap. Severity is high (CVSS 7.5). In filter.c in slapd in OpenLDAP before 2.4.50, LDAP search filters with nested boolean expressions can result in denial of service (daemon crash).

How urgent is CVE-2020-12243?

Priority 64/100. High severity; EPSS top 8%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Ubuntu vulnerabilities · Debian vulnerabilities · OpenLDAP vulnerabilities

Related CVEs

References

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