XSS in Zulip Server
CVE-2019-16216
Zulip server before 2.0.5 incompletely validated the MIME types of uploaded files. A user who is logged into the server could upload files of certain types to mount a stored cross-site scripting attack on other logged-in users. On a Zulip server using the default local uploads backend, the attack is only effective against browsers lacking support for Content-Security-Policy such as Internet Explorer 11. On a Zulip server using the S3 uploads backend, the attack is confined to the origin of the configured S3 uploads hostname and cannot reach the Zulip server itself.
Vulnerability class: XSS (Cross-Site Scripting)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.007 (50.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 51st percentile — 50.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.007 · newest: 0.007 · change: 0.000
Affected products
Weakness classification (CWE)
References
- blog.zulip.org/2019/09/11/zulip-server-2-0-5-security-release/ (Vendor Advisory)
- github.com/zulip/zulip/commit/1195841dfb9aa26b3b0dabc6f05d72e4af25be3e (Patch, Third Party Advisory)
Frequently asked questions
- What is CVE-2019-16216?
- CVE-2019-16216 is a medium-severity vulnerability in Zulip Server, classified under Cross-site Scripting. CVSS score: 5.4/10. Published 2019-09-18.
- How severe is CVE-2019-16216?
- Medium severity. CVSS v3 base score is 5.4 out of 10.