CVE-2020-25709: A flaw was found in OpenLDAP

Q: How do I fix CVE-2020-25709?

openldap: upgrade to 2.4.56; debian linux: mitigate or apply the listed mitigation; mac os x: upgrade to 10.14.6, 10.15.7. Exact commands for each OS are on this page.

Q: Is CVE-2020-25709 being exploited?

CVE-2020-25709 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-25709 affect?

CVE-2020-25709 affects openldap, debian linux, mac os x. Severity is high (CVSS 7.5). A flaw was found in OpenLDAP. This flaw allows an attacker who can send a malicious packet to be processed by OpenLDAP’s slapd server, to trigger an assertion failure. The highest threat from this vulnerability is to system availability.

Q: How urgent is CVE-2020-25709?

Priority 58/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

This month

HIGH 7.5REMOTEWATCHLISTUPGRADEMITIGATEUPGRADE

CVE-2020-25709 is a high-severity flaw (CVSS 7.5) affecting openldap, debian linux, mac os x. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A flaw was found in OpenLDAP. This flaw allows an attacker who can send a malicious packet to be processed by OpenLDAP’s slapd server, to trigger an assertion failure. The highest threat from this vulnerability is to system availability.

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.4% (top 11%)
CISA exploited list	No
Weakness	CWE-617
Published	2021-05-18
Last modified	2026-10-14

Publisher (CNA): Red Hat, Inc. · Vendor: apple · debian · openldap · redhat

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

Am I affected?

Timeline

2021-05-18 12:15 UTCPublished CVE record published
2026-10-14 10:17 UTCUpdated Record last modified

openldap openldap UPGRADE

Affected: < 2.4.56

Fixed in: 2.4.56

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy openldap || rpm -q openldap || openldap --version

2. UPGRADE to 2.4.56 (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: 9.0 · 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

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.

apple mac os x UPGRADE

Affected: >= 10.14.0 and < 10.14.6 · >= 10.15 and < 10.15.7 · 10.14.6 · 10.14.6 security_update_2019-004 · 10.14.6 security_update_2019-005 · 10.14.6 security_update_2019-006 · 10.14.6 security_update_2019-007 · 10.14.6 security_update_2020-001

Fixed in: 10.14.6, 10.15.7

Safe to downgrade to: a release before 10.14.0

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.

apple macos UPGRADE

Affected: >= 11.0 and < 11.0.1

Fixed in: 11.0.1

Safe to downgrade to: a release before 11.0

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.

redhat jboss core services 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 jboss-core-services || rpm -q jboss-core-services || jboss-core-services --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-2020-25709?

openldap: upgrade to 2.4.56; debian linux: mitigate or apply the listed mitigation; mac os x: upgrade to 10.14.6, 10.15.7. Exact commands for each OS are on this page.

Is CVE-2020-25709 being exploited?

CVE-2020-25709 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-2020-25709 affect?

CVE-2020-25709 affects openldap, debian linux, mac os x. Severity is high (CVSS 7.5). A flaw was found in OpenLDAP. This flaw allows an attacker who can send a malicious packet to be processed by OpenLDAP’s slapd server, to trigger an assertion failure. The highest threat from this vulnerability is to system availability.

How urgent is CVE-2020-25709?

Priority 58/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities · macOS vulnerabilities · OpenLDAP vulnerabilities · JBoss and WildFly vulnerabilities

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References

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