RedisDatabase / datastore
CVE-2021-32626
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, in-memory database that persists on disk. In affected versions specially crafted Lua scripts executing in Redis can cause the heap-based Lua stack to be overflowed, due to incomplete checks for this condition. This can result with heap corruption and potentially remote code execution. This problem exists in all versions of Redis with Lua scripting support, starting from 2.6. The problem is fixed in versions 6.2.6, 6.0.16 and 5.0.14. For users unable to update an additional workaround to mitigate the problem without patching the redis-server executable is to prevent users from executing Lua scripts. This can be done using ACL to restrict EVAL and EVALSHA commands.
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 analysisData overflows a buffer allocated on the heap, corrupting neighbouring heap structures and allocator metadata that a patient attacker can groom into control of execution. It is subtler than a stack overflow but just as dangerous. The fix is validating lengths before every write and using safe allocators and bounded operations.
General guidance for the heap-based buffer overflow class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →
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
>= 2.6, < 5.0.14>= 6.0.0, < 6.0.16>= 6.2.0, < 6.2.6
FedoraOperating system
= 33= 34= 35
Debian LinuxOperating system
= 10.0= 11.0all versionsall versions= 4.3= 4.4= 5.0CVSS 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
- 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
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 · scoped5.0.146.0.166.2.6
Redis 5.0.14, 6.0.16, or 6.2.6 (depending on which branch you are on)
- 1. Identify the currently installed Redis version using `redis-server --version` or `redis-cli INFO server`.
- 2. Determine the appropriate upgrade path based on current version: if < 5.0.14 upgrade to 5.0.14; if >= 6.0.0 and < 6.0.16 upgrade to 6.0.16; if >= 6.2.0 and < 6.2.6 upgrade to 6.2.6.
- 3. Back up the Redis data directory (default /var/lib/redis) and configuration file (/etc/redis/redis.conf).
- 4. Stop the Redis service: `systemctl stop redis` or `service redis stop`.
- 5. Upgrade Redis using the package manager (e.g., `apt-get update && apt-get install redis-server` for Debian/Ubuntu, or `yum update redis` for RHEL/Fedora).
- 6. Alternatively, download and install from source the appropriate fixed version from https://redis.io/download.
- 7. Start the Redis service: `systemctl start redis` or `service redis start`.
- 8. Verify the upgrade by running `redis-server --version` to confirm the version matches the target fixed release.
Generated from the published advisory — verify against the referenced sources before acting.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-32626 — 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-2021-32626 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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- Version or environment caveats, and links to real fixes
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