RedisDatabase / datastore
CVE-2021-32675
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. When parsing an incoming Redis Standard Protocol (RESP) request, Redis allocates memory according to user-specified values which determine the number of elements (in the multi-bulk header) and size of each element (in the bulk header). An attacker delivering specially crafted requests over multiple connections can cause the server to allocate significant amount of memory. Because the same parsing mechanism is used to handle authentication requests, this vulnerability can also be exploited by unauthenticated users. The problem is fixed in Redis versions 6.2.6, 6.0.16 and 5.0.14. An additional workaround to mitigate this problem without patching the redis-server executable is to block access to prevent unauthenticated users from connecting to Redis. This can be done in different ways: Using network access control tools like firewalls, iptables, security groups, etc. or Enabling TLS and requiring users to authenticate using client side certificates.
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 analysisThe application allocates memory, connections, or handles in response to a request without enforcing any cap, so a modest amount of malicious traffic exhausts the resource and denies service to everyone else. The fix is enforcing quotas, limits, and timeouts on what any single request or client can consume.
General guidance for the resource allocation without limits 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
>= 5.0.0, < 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
- 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
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 (choose the appropriate branch based on your current major version)
- 1. Identify current Redis version by running `redis-server --version` or `redis-cli INFO server`
- 2. Create a backup of Redis data directory (default /var/lib/redis) and configuration files (default /etc/redis/)
- 3. Stop the Redis service: `systemctl stop redis` or `service redis stop`
- 4. Upgrade Redis to version 5.0.14, 6.0.16, or 6.2.6 using your system's package manager (apt-get, yum/dnf) or by compiling from source
- 5. If using a package manager, run: `apt-get update && apt-get install redis-server` (Debian/Ubuntu) or `dnf update redis` (Fedora)
- 6. Verify the upgrade was successful by checking version: `redis-server --version`
- 7. Start the Redis service: `systemctl start redis` or `service redis start`
- 8. Test Redis functionality: `redis-cli ping` should return PONG
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-2021-32675 — 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-2021-32675 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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