CVE-2024-37303
Synapse unauthenticated writes to the media repository allow planting of problematic content
Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- Low
- Availability
- None
Exploit likelihood
What each source reports
CVE List Score used
Synapse unauthenticated writes to the media repository allow planting of problematic content
Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.
- Record
CVE-2024-37303- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-306
- Updated
- 2026-11-02
EUVDEUVD-2024-3472
Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.
- Record
EUVD-2024-3472- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-03
GitHub AdvisoriesGHSA-gjgr-7834-rhxr
Synapse's unauthenticated writes to the media repository allow planting of problematic content
Impact
Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository.
Patches
Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.
Workarounds
Though extremely limited, server operators can use more strict rate limits based on IP address.
References
For more information
If you have any questions or comments about this advisory, please email us at security at element.io.
- Record
GHSA-gjgr-7834-rhxr- CVSS 4.0
- 6.9 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-306
- Updated
- 2026-11-02
NVD
Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.
- Record
CVE-2024-37303- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-306
- Updated
- 2026-11-02
OSVALPINE-CVE-2024-37303
Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.
- Record
ALPINE-CVE-2024-37303- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-03
OSV
Synapse unauthenticated writes to the media repository allow planting of problematic content
Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.
- Record
CVE-2024-37303- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Weakness
- CWE-306
- Updated
- 2026-11-02
Show 5 moreShow less
OSVDEBIAN-CVE-2024-37303
Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.
- Record
DEBIAN-CVE-2024-37303- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-02
OSVGHSA-gjgr-7834-rhxr
Synapse's unauthenticated writes to the media repository allow planting of problematic content
Impact
Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository.
Patches
Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.
Workarounds
Though extremely limited, server operators can use more strict rate limits based on IP address.
References
For more information
If you have any questions or comments about this advisory, please email us at security at element.io.
- Record
GHSA-gjgr-7834-rhxr- CVSS 4.0
- 6.9 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-306
- Updated
- 2026-11-02
OSVPYSEC-2024-287
Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.
- Record
PYSEC-2024-287- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-02
OSVUBUNTU-CVE-2024-37303
Synapse is an open-source Matrix homeserver. Synapse before version 1.106 allows, by design, unauthenticated remote participants to trigger a download and caching of remote media from a remote homeserver to the local media repository. Such content then also becomes available for download from the local homeserver in an unauthenticated way. The implication is that unauthenticated remote adversaries can use this functionality to plant problematic content into the media repository. Synapse 1.106 introduces a partial mitigation in the form of new endpoints which require authentication for media downloads. The unauthenticated endpoints will be frozen in a future release, closing the attack vector.
- Record
UBUNTU-CVE-2024-37303- CVSS 3.1
- 5.3 Medium
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Updated
- 2026-11-02
OSVopenSUSE-SU-2024:14541-1 No score
matrix-synapse-1.120.2-1.1 on GA media
These are all security issues fixed in the matrix-synapse-1.120.2-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:14541-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
matrix-synapsePyPI |
before 1.106 | 1.106 |
synapseAlpine:v3.20 |
before 1.110.0-r0 | 1.110.0-r0 |
synapseAlpine:v3.21 |
before 1.110.0-r0 | 1.110.0-r0 |
synapseAlpine:v3.22 |
before 1.110.0-r0 | 1.110.0-r0 |
synapseAlpine:v3.23 |
before 1.110.0-r0 | 1.110.0-r0 |
synapseAlpine:v3.24 |
before 1.110.0-r0 | 1.110.0-r0 |
matrix-synapsePyPI |
before 1.106, plus listed versions 0.33.50.33.5.10.33.60.33.6rc10.33.7 Show 45 moreShow less0.33.7rc10.33.7rc20.33.80.33.8rc20.33.90.34.00.34.0.10.34.0rc10.34.0rc20.34.1.10.99.00.99.0rc10.99.0rc20.99.0rc30.99.0rc40.99.10.99.1.10.99.1rc10.99.1rc20.99.20.99.2rc10.99.30.99.3.10.99.3.20.99.3rc10.99.40.99.4rc10.99.50.99.5.10.99.5.20.99.5rc11.0.01.0.0rc11.0.0rc21.0.0rc31.1.01.1.0rc11.1.0rc21.10.01.10.0rc11.10.0rc21.10.0rc31.10.0rc51.10.11.100.0 |
1.106 |
matrix-synapsePyPI |
before 1.106.0, plus listed versions 0.33.50.33.5.10.33.60.33.6rc10.33.7 Show 45 moreShow less0.33.7rc10.33.7rc20.33.80.33.8rc20.33.90.34.00.34.0.10.34.0rc10.34.0rc20.34.1.10.99.00.99.0rc10.99.0rc20.99.0rc30.99.0rc40.99.10.99.1.10.99.1rc10.99.1rc20.99.20.99.2rc10.99.30.99.3.10.99.3.20.99.3rc10.99.40.99.4rc10.99.50.99.5.10.99.5.20.99.5rc11.0.01.0.0rc11.0.0rc21.0.0rc31.1.01.1.0rc11.1.0rc21.10.01.10.0rc11.10.0rc21.10.0rc31.10.0rc51.10.11.100.0 |
1.106.0 |
matrix-synapseUbuntu:Pro:18.04:LTS |
All versions, plus listed versions 0.19.2+dfsg-60.24.0+dfsg-10.24.0+dfsg-1ubuntu0.1~esm10.24.0+dfsg-1ubuntu0.1~esm4 |
None known |
matrix-synapseUbuntu:Pro:20.04:LTS |
All versions, plus listed versions 1.3.0-11.4.0-11.5.0-11.5.1-11.6.0-1 Show 12 moreShow less1.6.1-11.7.0-21.7.1-11.7.2-11.7.3-11.8.0-11.9.0-11.9.1-11.10.0-11.10.0-21.11.0-11.11.0-1ubuntu0.1~esm2 |
None known |
matrix-synapseUbuntu:Pro:22.04:LTS |
All versions, plus listed versions 1.39.0-11.47.0-21.47.1-11.48.0-11.49.0-1 Show 7 moreShow less1.49.2-11.50.1-11.50.2-11.51.0-11.52.0-11.53.0-11.53.0-1ubuntu0.1~esm2 |
None known |
matrix-synapseUbuntu:24.04:LTS |
All versions, plus listed versions 1.90.0-11.100.0-1ubuntu1 |
None known |
matrix-synapseopenSUSE:Tumbleweed From an advisory covering 6 CVEs |
before 1.120.2-1.1 | 1.120.2-1.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| affected, aliases, references | OSV | |
| affected | ||
| aliases, published | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2024-37303 is a medium vulnerability (CVSS 5.3) in Element-hq Synapse, published December 3, 2024. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.43%, the 37th percentile. Fixed in matrix-synapse 1.106.
References
github.com/element-hq/synapse/security/advisories/GHSA-gjgr-7834-rhxr
nvd.nist.gov/vuln/detail/CVE-2024-37303
security.alpinelinux.org/vuln/CVE-2024-37303
Show 11 moreShow less
security-tracker.debian.org/tracker/CVE-2024-37303
ubuntu.com/security/CVE-2024-37303
cve.org/CVERecord?id=CVE-2024-37303
suse.com/security/cve/CVE-2024-37302
Left out here: 656 versions. The JSON record has them.