Vulnerability · Published Nov 23, 2021 · Assigned by GitHub_M
CVE-2021-41281Path traversal in Matrix Synapse
High 7.5
In plain English
A high-severity path traversal 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 1.6% (higher than 76% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
Synapse is a package for Matrix homeservers written in Python 3/Twisted. Prior to version 1.47.1, Synapse instances with the media repository enabled can be tricked into downloading a file from a remote server into an arbitrary directory. No authentication is required for the affected endpoint. The last 2 directories and file name of the path are chosen randomly by Synapse and cannot be controlled by an attacker, which limits the impact. Homeservers with the media repository disabled are unaffected. Homeservers with a federation whitelist are also unaffected, since Synapse will check the remote hostname, including the trailing `../`s, against the whitelist. Server administrators should upgrade to 1.47.1 or later. Server administrators using a reverse proxy could, at the expense of losing media functionality, may block the certain endpoints as a workaround. Alternatively, non-containerized deployments can be adapted to use the hardened systemd config.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.20 | synapse | 1.47.1-r0 | ALPINE-CVE-2021-41281 |
| Alpine:v3.21 | synapse | 1.47.1-r0 | ALPINE-CVE-2021-41281 |
| Alpine:v3.22 | synapse | 1.47.1-r0 | ALPINE-CVE-2021-41281 |
| Alpine:v3.23 | synapse | 1.47.1-r0 | ALPINE-CVE-2021-41281 |
| Alpine:v3.24 | synapse | 1.47.1-r0 | ALPINE-CVE-2021-41281 |
| Debian:14 | matrix-synapse | 1.47.1-1 | DEBIAN-CVE-2021-41281 |
| PyPI | matrix-synapse | 1.47.1 | GHSA-3hfw-x7gx-437c |
| PyPI | matrix-synapse | 1.47.1 | PYSEC-2021-436 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| matrix-org | synapse | < 1.47.1 |
Weakness: CWE-22 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
References
- https://github.com/matrix-org/synapse/security/advisories/GHSA-3hfw-x7gx-437c x_refsource_CONFIRM
- https://github.com/matrix-org/synapse/commit/91f2bd090 x_refsource_MISC
- https://github.com/matrix-org/synapse/releases/tag/v1.47.1 x_refsource_MISC
- FEDORA-2021-2f9dcdbace vendor-advisory, x_refsource_FEDORA
- FEDORA-2021-9758549fce vendor-advisory, x_refsource_FEDORA