#VU76259 Key management errors in Synapse - CVE-2019-5885

Vulnerability identifier: #VU76259

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2019-5885

CWE-ID: CWE-320

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Synapse
Server applications / Conferencing, Collaboration and VoIP solutions

Vendor: Matrix.org

Description

The vulnerability allows a remote attacker to impersonate application users.

The vulnerability exists due to usage of a weak and predictable secret key if the macaroon_secret_key authentication parameter is not set. A remote attacker can impersonate other application users.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Synapse: before 0.34.0.1

---

External links
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/
https://matrix.org/blog/2019/01/10/critical-security-update-synapse-0-34-0-1-synapse-0-34-1-1/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VMCLO5PUPBA756UKY72PKUWL4RRM4W6K/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/32Y6KD3OAHCG5P33HC2QEX3NUZOSXCGZ/

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.