CVE-2021-21394
published 2021-04-12CVE-2021-21394: Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP…
PriorityP335medium6.5CVSS 3.1
AVNACLPRLUINSUCNINAH
EPSS
1.54%
72.1th percentile
Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.28.0 Synapse is missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion. Note that the groups feature is not part of the Matrix specification and the chosen maximum lengths are arbitrary. Not all clients might abide by them. Refer to referenced GitHub security advisory for additional details including workarounds.
Affected
4 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| debian | matrix-synapse | < matrix-synapse 1.28.0-1 (forky) | matrix-synapse 1.28.0-1 (forky) |
| fedoraproject | fedora | — | — |
| matrix-org | synapse | < 1.28.0 | 1.28.0 |
| matrix | synapse | < 1.28.0 | 1.28.0 |
CVSS provenance
nvdv3.16.5MEDIUMCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
nvdv2.04.0MEDIUMAV:N/AC:L/Au:S/C:N/I:N/A:P
osv6.5MEDIUM
vendor_debian5.3MEDIUM
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Debian
CVE-2021-21394: matrix-synapse - Synapse is a Matrix reference homeserver written in python (pypi package matrix-...
vendor_debian·2021·CVSS 5.3
CVE-2021-21394 [MEDIUM] CVE-2021-21394: matrix-synapse - Synapse is a Matrix reference homeserver written in python (pypi package matrix-...
Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.28.0 Synapse is missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion. Note that the groups feature is not part of the Matrix specification and the chosen maximum lengths are arbitrary. Not all clients might abide by them. Refer to referenced GitHub security advisory for additional details including workarounds.
Scope: local
forky: resolved (fixed in 1.28.0-1)
sid: resolved (fixed in 1.28.0-1)
OSV
Denial of service (via resource exhaustion) due to improper input validation on third-party identifier endpoints
osv·2021-04-13
CVE-2021-21394 [MEDIUM] Denial of service (via resource exhaustion) due to improper input validation on third-party identifier endpoints
Denial of service (via resource exhaustion) due to improper input validation on third-party identifier endpoints
### Impact
Missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion.
### Patches
The issue is fixed by #9321.
### Workarounds
Depending on the needs and configuration of the homeserver a few options are available:
1. Using email as third-party identifiers be disabled by not configuring the `email` setting.
2. Using phone numbers as third-party identifiers can be disabled by ensuring that `account_threepid_delegates.msisdn` is not configured.
3. Additionally, the affected endpoint patterns can be blocked at a reverse proxy:
* `^/_matrix/client/(r0|uns
GHSA
Denial of service (via resource exhaustion) due to improper input validation on third-party identifier endpoints
ghsa·2021-04-13
CVE-2021-21394 [MEDIUM] CWE-20 Denial of service (via resource exhaustion) due to improper input validation on third-party identifier endpoints
Denial of service (via resource exhaustion) due to improper input validation on third-party identifier endpoints
### Impact
Missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion.
### Patches
The issue is fixed by #9321.
### Workarounds
Depending on the needs and configuration of the homeserver a few options are available:
1. Using email as third-party identifiers be disabled by not configuring the `email` setting.
2. Using phone numbers as third-party identifiers can be disabled by ensuring that `account_threepid_delegates.msisdn` is not configured.
3. Additionally, the affected endpoint patterns can be blocked at a reverse proxy:
* `^/_matrix/client/(r0|uns
OSV
CVE-2021-21394: Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse)
osv·2021-04-12·CVSS 6.5
CVE-2021-21394 [MEDIUM] CVE-2021-21394: Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse)
Synapse is a Matrix reference homeserver written in python (pypi package matrix-synapse). Matrix is an ecosystem for open federated Instant Messaging and VoIP. In Synapse before version 1.28.0 Synapse is missing input validation of some parameters on the endpoints used to confirm third-party identifiers could cause excessive use of disk space and memory leading to resource exhaustion. Note that the groups feature is not part of the Matrix specification and the chosen maximum lengths are arbitrary. Not all clients might abide by them. Refer to referenced GitHub security advisory for additional details including workarounds.
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
https://github.com/matrix-org/synapse/pull/9321https://github.com/matrix-org/synapse/pull/9393https://github.com/matrix-org/synapse/security/advisories/GHSA-w9fg-xffh-p362https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY/https://pypi.org/project/matrix-synapse/https://github.com/matrix-org/synapse/pull/9321https://github.com/matrix-org/synapse/pull/9393https://github.com/matrix-org/synapse/security/advisories/GHSA-w9fg-xffh-p362https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/TNNAJOZNMVMXM6AS7RFFKB4QLUJ4IFEY/https://pypi.org/project/matrix-synapse/
2021-04-12
Published