Vulnerability · Published Dec 9, 2020 · Assigned by GitHub_M
CVE-2020-26257Denial of service attack via incorrect parameters to federation APIs
Medium 6.5
In plain English
A medium-severity uncontrolled resource consumption in synapse from matrix-org. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 2.4% (higher than 84% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Matrix is an ecosystem for open federated Instant Messaging and VoIP. Synapse is a reference "homeserver" implementation of Matrix. A malicious or poorly-implemented homeserver can inject malformed events into a room by specifying a different room id in the path of a `/send_join`, `/send_leave`, `/invite` or `/exchange_third_party_invite` request. This can lead to a denial of service in which future events will not be correctly sent to other servers over federation. This affects any server which accepts federation requests from untrusted servers. The Matrix Synapse reference implementation before version 1.23.1 the implementation is vulnerable to this injection attack. Issue is fixed in version 1.23.1. As a workaround homeserver administrators could limit access to the federation API to trusted servers (for example via `federation_domain_whitelist`).
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | synapse | 1.24.0-r0 | ALPINE-CVE-2020-26257 |
| Alpine:v3.21 | synapse | 1.24.0-r0 | ALPINE-CVE-2020-26257 |
| Alpine:v3.22 | synapse | 1.24.0-r0 | ALPINE-CVE-2020-26257 |
| Alpine:v3.23 | synapse | 1.24.0-r0 | ALPINE-CVE-2020-26257 |
| Alpine:v3.24 | synapse | 1.24.0-r0 | ALPINE-CVE-2020-26257 |
| Debian:14 | matrix-synapse | 1.24.0-1 | DEBIAN-CVE-2020-26257 |
| PyPI | matrix-synapse | 1.23.1 | GHSA-hxmp-pqch-c8mm |
| PyPI | matrix-synapse | 1.23.1 | PYSEC-2020-236 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| matrix-org | synapse | < 1.23.1 |
Weakness: CWE-400, CWE-79 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
References
- https://github.com/matrix-org/synapse/security/advisories/GHSA-hxmp-pqch-c8mm x_refsource_CONFIRM
- https://github.com/matrix-org/synapse/pull/8776 x_refsource_MISC
- https://github.com/matrix-org/synapse/commit/3ce2f303f15f6ac3dc352298972dc6e04d9b7a8b x_refsource_MISC
- https://github.com/matrix-org/synapse/blob/develop/CHANGES.md#synapse-1231-2020-12-09 x_refsource_MISC
- FEDORA-2020-a2172c484d vendor-advisory, x_refsource_FEDORA
- FEDORA-2020-eeb66c2ece vendor-advisory, x_refsource_FEDORA