CVE-2021-35945
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 · uneditedCouchbase Server 6.5.x, 6.6.0 through 6.6.2, and 7.0.0, has a Buffer Overflow. A specially crafted network packet sent from an attacker can crash memcached.
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 confidenceA buffer overflow vulnerability exists in the memcached component of Couchbase Server versions 6.5.x, 6.6.0-6.6.2, and 7.0.0. An unauthenticated remote attacker can send a specially crafted network packet to trigger the overflow, causing memcached 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>= 4.5.0, <= 5.5.6>= 6.0.0, <= 6.0.5>= 6.5.0, <= 6.5.2>= 6.6.0, <= 6.6.2= 7.0.0CVSS 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
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/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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Identify Couchbase Server versionRun 'couchbase-cli server-info' or check the web console (Settings > Server Nodes) to find the installed versionAffected if The version falls within any of these ranges: 4.5.0-5.5.6, 6.0.0-6.0.5, 6.5.0-6.5.2, 6.6.0-6.6.2, or 7.0.0
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Confirm memcached component is runningCheck if the memcached service is active using 'systemctl status memcached' or by querying the Couchbase cluster status via 'couchbase-cli server-list'Affected if Memcached process is running as part of the Couchbase Server deployment
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Verify memcached network exposureCheck listening ports with 'netstat -tlnp | grep -E "11210|11211"' or 'ss -tlnp | grep -E "11210|11211"' to see if memcached ports are bound to network interfacesAffected if Memcached ports (11210, 11211) are bound to a reachable network interface rather than localhost only
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Check firewall or network access controlsReview iptables, security groups, or network ACLs to determine if memcached ports are accessible from untrusted networksAffected if Memcached ports are open to untrusted network segments or the internet without restriction
You are affected if Couchbase Server version is within the vulnerable ranges AND the memcached component is network-accessible to untrusted attackers.
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 dataUpgrade Couchbase Server to a patched version (6.6.3 or later for 6.6.x branches, 7.0.1 or later for 7.0.x). If immediate upgrade is not possible, restrict network access to memcached ports using firewall rules or network segmentation.
- Consultation2.0 h
- Implementation3.0 h
- Testing2.0 h
- Review / QA1.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-35945 — 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-2021-35945 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
- No weaponised exploit code, or anything meant to cause harm
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