RedisDatabase / datastore · Redislabs
CVE-2021-29477
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 · uneditedRedis is an open source (BSD licensed), in-memory data structure store, used as a database, cache, and message broker. An integer overflow bug in Redis version 6.0 or newer could be exploited using the `STRALGO LCS` command to corrupt the heap and potentially result with remote code execution. The problem is fixed in version 6.2.3 and 6.0.13. An additional workaround to mitigate the problem without patching the redis-server executable is to use ACL configuration to prevent clients from using the `STRALGO LCS` command.
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 confidenceInteger overflow vulnerability in Redis versions 6.0+ when processing the STRALGO LCS (Longest Common Subsequence) command. Exploitation allows heap corruption leading to potential remote code execution.
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
RedisDatabase / datastore
>= 6.0.0, < 6.0.13>= 6.2.0, < 6.2.3
FedoraOperating system
= 33= 34CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 installed Redis versionRun `redis-server --version` or `redis-cli INFO server | grep redis_version` to determine the exact version numberAffected if Version is 6.0.0 to 6.0.12, or 6.2.0 to 6.2.2
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Verify STRALGO command existsRun `redis-cli COMMAND INFO STRALGO` to confirm the command is available in the Redis instanceAffected if The command returns a valid response showing STRALGO is loaded
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Check command execution permissionRun `redis-cli ACL GETUSER <username>` or test with `redis-cli STRALGO LCS ...` to see if the command can be executedAffected if The STRALGO command executes without permission errors for the connecting user
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Confirm Redis is exposedCheck if Redis port (default 6379) is listening on network interfaces by reviewing netstat/ss output or Redis bind configuration in redis.confAffected if Redis is bound to a non-loopback address and accessible from network
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.
dbcve · scoped6.0.136.2.3
Primary: Upgrade Redis to version 6.2.3 or 6.0.13. Alternative: Configure Redis ACL to deny clients access to the STRALGO LCS command.
Redis 6.0.13 or 6.2.3 (or later)
- Upgrade Redis to version 6.0.13 or higher (6.2.3 recommended)
- Restart the Redis service after applying the upgrade
- Verify the fix by running `redis-server --version` to confirm the installed version
- Optionally, as an additional defense-in-depth measure, configure ACL to restrict the STRALGO LCS command: add `rename-command STRALGO ""` to redis.conf
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Redis
Scoped from the published advisory
- Consultation2.0 h
- Implementation4.0 h
- Testing2.0 h
- Review / QA1.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-29477 — 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-2021-29477 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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