Description
Synapse is an open source Matrix homeserver implementation. A malicious server can craft events which, when received, prevent Synapse version up to 1.127.0 from federating with other servers. The vulnerability has been exploited in the wild and has been fixed in Synapse v1.127.1. No known workarounds are available.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| element-hq | synapse | < 1.127.1 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 24.04 LTS | matrix-synapse | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 22.04 LTS | matrix-synapse | No fix yet | — |
| Ubuntu Pro 20.04 LTS | matrix-synapse | No fix yet | — |
| Ubuntu Pro 18.04 LTS | matrix-synapse | No fix yet | — |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | matrix-synapse | 1.127.1-1.1 | openSUSE-SU-2025:14939-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | synapse | 1.127.1-r0 | — |
| Alpine v3.23 | synapse | 1.127.1-r0 | — |
| Alpine v3.22 | synapse | 1.127.1-r0 | — |
| Alpine v3.21 | synapse | 1.127.1-r0 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | matrix-synapse | < 1.127.1 | 1.127.1 | GHSA-v56r-hwv5-mxg6 |
Advisories 1
- openSUSE-SU-2025:14939-1 matrix-synapse-1.127.1-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026