GHSA-3hfw-x7gx-437c · Severity: high · Ecosystem: pip — Path traversal in Matrix Synapse
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.
Conclusion & alert: CVE-2021-41281 is rated Moderate Risk (55.9/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.51%). Mandatory action: Review affected assets and schedule remediation.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.52% | 1.51% | +0.99% |
| 2 | 2025-03-30 | 1.06% | 0.52% | -0.54% |
| 3 | 2025-03-29 | — | 1.06% | — |
Full EPSS history (12 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 7.5 | 3.1 | HIGH |
|
3.9 | 3.6 | [email protected] |
| 4.3 | 2.0 | MEDIUM |
|
8.6 | 2.9 | [email protected] |
GHSA-3hfw-x7gx-437c · Severity: high · Ecosystem: pip — Path traversal in Matrix Synapse
| vendor | priority | summary | link |
|---|---|---|---|
alpine
|
high | CVE-2021-41281: 1 source package rows (synapse); 19 state rows across 7 repos (3.17-community, 3.18-community, 3.19-community, 3.20-community, 3.21-community, 3.22-community, edge-community); fixed 7, open 12. | https://security.alpinelinux.org/vuln/CVE-2021-41281 |
debian
|
not yet assigned | CVE-2021-41281 not yet assigned priority: Debian including 1 source packages (matrix-synapse), 2 status rows across 2 suites (forky, sid): resolved 2. | https://security-tracker.debian.org/tracker/CVE-2021-41281 |
ubuntu
|
medium | CVE-2021-41281 medium priority: Ubuntu including 1 source packages (matrix-synapse), 13 status rows across 13 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, trusty, upstream, xenial): ignored 5, not-affected 4, needed 3, released 1. | https://ubuntu.com/security/CVE-2021-41281 |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| matrix | synapse | < 1.47.1 | cpe:2.3:a:matrix:synapse:*:*:*:*:*:*:*:* |
| fedoraproject | fedora | 34 | cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* |
| fedoraproject | fedora | 35 | cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:* |