CVE-2026-14940: A heap-buffer-overflow flaw was found in 389 Directory Server (389-ds-base)

Routine

MEDIUM 5.3REMOTEWATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2026-14940 is a medium-severity flaw (CVSS 5.3) affecting directory server, 389 directory server, enterprise linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A heap-buffer-overflow flaw was found in 389 Directory Server (389-ds-base). When normalizing a Distinguished Name (DN) that contains a legacy-quoted value encoding a multivalued nested Relative Distinguished Name (RDN), the server can write past the end of a heap allocation while sorting RDN attribute-value pairs. An unauthenticated remote attacker can trigger this condition by sending an LDAP operation whose DN reaches the DN normalization rout

Why this priority

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

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-122
Published	2026-07-07
Last modified	2026-07-09

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

Last updated 2026-07-09 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-07 15:16 UTCPublished CVE record published
2026-07-09 20:20 UTCUpdated Record last modified

redhat directory server DOWNGRADE

Affected: 11.0 · 12.0 · 13.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 11.0

1. Check installed version

apt-cache policy directory-server || rpm -q directory-server || directory-server --version

2. No fixed release: DOWNGRADE to a release before 11.0 (Debian / Ubuntu)

apt-cache madison directory-server sudo apt install directory-server=<VERSION_BEFORE_11.0> sudo apt-mark hold directory-server

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list directory-server sudo dnf downgrade directory-server-<VERSION_BEFORE_11.0> sudo dnf versionlock add directory-server

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

redhat 389 directory server MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

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 enterprise linux MITIGATE

Affected: 7.0 · 8.0 · 9.0 · 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 7.0

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.

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-2026-14940?

directory server: downgrade or apply the listed mitigation; 389 directory server: mitigate or apply the listed mitigation; enterprise linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-14940 being exploited?

CVE-2026-14940 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-2026-14940 affect?

CVE-2026-14940 affects directory server, 389 directory server, enterprise linux. Severity is medium (CVSS 5.3). A heap-buffer-overflow flaw was found in 389 Directory Server (389-ds-base). When normalizing a Distinguished Name (DN) that contains a legacy-quoted value encoding a multivalued nested Relative Distinguished Name (RDN), the server can writ

How urgent is CVE-2026-14940?

Priority 39/100. Remotely exploitable, no login, no user action; On your watchlist

Related CVEs

CVE-2026-15722 HIGH 7.5 DOWNGRADE MITIGATE A stack buffer overflow flaw was found in 389 Directory Server (389-ds-base)
CVE-2026-11770 HIGH 7.5 DOWNGRADE MITIGATE A flaw was found in 389 Directory Server
CVE-2026-18651 MEDIUM 5.4 DOWNGRADE MITIGATE A flaw was found in 389 Directory Server
CVE-2026-14969 MEDIUM 4.4 DOWNGRADE MITIGATE A flaw was found in 389-ds-base where the LDBM backend attribute encryption uses a hardcoded static initializa
CVE-2026-15041 LOW 3.7 DOWNGRADE MITIGATE A flaw was found in 389 Directory Server

References

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