389 Directory ServerOperating system · Redhat
CVE-2021-3514
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedWhen using a sync_repl client in 389-ds-base, an authenticated attacker can cause a NULL pointer dereference using a specially crafted query, causing a crash.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceIn 389-ds-base, an authenticated attacker exploiting the sync_repl (synchronous replication) client can send a specially crafted query that triggers a NULL pointer dereference, causing the directory server to crash and resulting in denial of service.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
389 Directory ServerOperating system
all versionsCVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify 389 Directory Server is installedRun 'rpm -qa | grep 389-ds-base' or check for the 'ns-slapd' process running (directory server daemon)Affected if 389-ds-base package is installed or ns-slapd process is running
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Check if sync_repl is configuredLook for 'sync' in the directory server configuration files (typically in dse.ldif or cn=changelog5,cn=config) or check replication configuration for 'nsds5ReplicaSync' attributesAffected if Synchronous replication (sync_repl) is enabled in the server configuration
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Verify sync_repl client access settingsReview the replication agreement settings in cn=replica,cn=dc=yourdomain,cn=domains,cn=config for sync consumer configurations and check who can connect as a sync_repl clientAffected if sync_repl accepts connections from untrusted or external authenticated users
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Confirm patch statusCheck if the installed package has the CVE-2021-3514 fix applied by querying the RPM changelog: 'rpm -q --changelog 389-ds-base | grep -i CVE-2021-3514'Affected if The CVE-2021-3514 fix entry is absent from the package changelog
If the server runs 389-ds-base with sync_repl enabled and the CVE-2021-3514 patch is not applied, the environment is vulnerable to denial of service via crafted sync_repl queries.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataApply the vendor patch for CVE-2021-3514 to address the NULL pointer dereference in the sync_repl component. Additionally, restrict sync_repl client access to trusted authenticated users only to reduce attack surface.
Fix this in 389 Directory Server
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,656.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-3514 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-3514 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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