CVE-2023-49952
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 · uneditedMastodon 4.1.x before 4.1.17 and 4.2.x before 4.2.9 allows a bypass of rate limiting via a crafted HTTP request header.
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 confidenceMastodon versions 4.1.x before 4.1.17 and 4.2.x before 4.2.9 contain a rate limiting bypass vulnerability where attackers can circumvent rate restrictions by sending crafted HTTP request headers. The application's rate limiting logic improperly handles certain HTTP headers, allowing attackers to bypass intended throttling limits.
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>= 4.1.0, < 4.1.17>= 4.2.0, < 4.2.9CVSS 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
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
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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Check installed Mastodon versionRun `git log -1 --format=%H %s` in the Mastodon application directory, or check the admin dashboard under Site Settings > About for the version number. On packaged installations, check `/opt/mastodon/VERSION` or similar package-specific paths.Affected if Version is 4.1.0 through 4.1.16, or 4.2.0 through 4.2.8
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Confirm rate limiting is activeRate limiting is typically enabled by default in production environments. Verify by checking the Rails configuration file (config/environments/production.rb) for `config.middleware.use Rack::Attack` or similar rate limiting middleware configurations.Affected if Rate limiting middleware is loaded and active in the environment (default in production)
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Verify HTTP header processing is in useMastodon processes client-provided HTTP headers (X-Forwarded-For, Client-IP, etc.) for request identification. This is standard in deployments behind proxies or load balancers. Check if the application processes these headers via the Rails configuration.Affected if The application processes X-Forwarded-For or similar forwarded headers from clients (typical in production deployments)
You are affected if your Mastodon version is 4.1.0-4.1.16 or 4.2.0-4.2.8 and rate limiting is enabled, which is the default production configuration.
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 · scoped4.1.174.2.9
Upgrade Mastodon to version 4.1.17 or later for the 4.1.x branch, or version 4.2.9 or later for the 4.2.x branch to receive the security patch.
Mastodon 4.2.9 (or 4.1.17 for the 4.1.x line)
- 1. Backup your Mastodon database and file system before proceeding
- 2. Stop the Mastodon services (Puma, Sidekiq, streaming API)
- 3. Navigate to your Mastodon installation directory
- 4. Run the upgrade command for your deployment method (e.g., `git pull` for source installations, or use your package manager for Docker/systemd deployments)
- 5. Run database migrations if required: `RAILS_ENV=production bundle exec rails db:migrate`
- 6. Precompile assets: `RAILS_ENV=production bundle exec rails assets:precompile`
- 7. Restart all Mastodon services
- 8. Verify the upgrade by checking the version in the admin interface or via the API
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2023-49952 — 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-2023-49952 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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