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SynapseApplication · Matrix

CVE-2024-52815

MEDIUM · 5.3 CVSS v3.1 Developing Published 2024-12-03
Fix available
A fix is available. Upgrade to 1.120.1 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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 · unedited
Synapse is an open-source Matrix homeserver. Synapse versions before 1.120.1 fail to properly validate invites received over federation. This vulnerability allows a malicious server to send a specially crafted invite that disrupts the invited user's /sync functionality. Synapse 1.120.1 rejects such invalid invites received over federation and restores the ability to sync for affected users.

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 · low confidence
Developing — this CVE was published recently and its authoritative NVD entry is still being established, so we're holding a technical summary until the source data settles rather than publish something unreliable. Re-checking after 2026-07-31.

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
SynapseApplication
Affected:< 1.120.1

CVSS 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
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 · scoped
Upgrade available Upgrade to 1.120.1 or later
Fixed in 1.120.1
Recommended fix High confidence

Synapse 1.120.1

  1. 1. Check current Synapse version using 'python -m synapse.app.homeserver --version' or checking your package manager
  2. 2. Backup your Synapse configuration directory (usually /etc/matrix-synapse or /etc/synapse) and database before upgrading
  3. 3. Upgrade Synapse to version 1.120.1 or later using your package manager (e.g., 'apt update && apt install matrix-synapse' or 'pip install --upgrade matrix-synapse')
  4. 4. Restart the Synapse service to apply the update (e.g., 'systemctl restart matrix-synapse' or 'synctl restart')
  5. 5. Verify the new version is running and test that /sync functionality works correctly
  6. 6. Monitor logs for any issues related to invite processing
Caveat Review Synapse 1.120 release notes for any breaking changes before upgrading; major version upgrades may require migration steps

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $1,600. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2024-52815 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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