Description
Matrix Synapse before 0.34.0.1, when the macaroon_secret_key authentication parameter is not set, uses a predictable value to derive a secret key and other secrets which could allow remote attackers to impersonate users.
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 Pro 18.04 LTS | matrix-synapse | 0.24.0+dfsg-1ubuntu0.1~esm1 | USN-6076-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | matrix-synapse | 1.43.0-1.1 | openSUSE-SU-2024:11041-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | matrix-synapse | < 0.34.0.1 | 0.34.0.1 | GHSA-jrqm-v8cv-53ww |
Advisories 2
- USN-6076-1 matrix-synapse vulnerabilities Ubuntu Security Notices (USN) · Feb 10, 2026
- openSUSE-SU-2024:11041-1 matrix-synapse-1.43.0-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
References
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/32Y6KD3OAHCG5P33HC2QEX3NUZOSXCGZ/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VMCLO5PUPBA756UKY72PKUWL4RRM4W6K/
- https://matrix.org/blog/2019/01/10/critical-security-update-synapse-0-34-0-1-synapse-0-34-1-1/
- https://matrix.org/blog/2019/01/15/further-details-on-critical-security-update-in-synapse-affecting-all-versions-prior-to-0-34-1-cve-2019-5885/