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Vulnerability record · CVE-2021-3866 · published 20 January 2022

CVE-2021-3866: Zulip cross-site scripting vulnerability

Zulip · Zulip

Cross-site Scripting (XSS) - Stored in GitHub repository zulip/zulip more than and including 44f935695d452cc3fb16845a0c6af710438b153d and prior to 3eb2791c3e9695f7d37ffe84e0c2184fae665cb6.

5.4 CVSS 3.1 Medium EPSS 0.89% · top 42.2% CWE-79 · Cross-site scripting
5.4CVSS 3.1 base score, v2 3.5
0.89%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References, 2 tagged exploit
17 Jun 2026Last modified by NVD

Description

Cross-site Scripting (XSS) - Stored in GitHub repository zulip/zulip more than and including 44f935695d452cc3fb16845a0c6af710438b153d and prior to 3eb2791c3e9695f7d37ffe84e0c2184fae665cb6.

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://blog.zulip.com/2022/01/19/cve-2021-3866/ Vendor Advisory
https://github.com/zulip/zulip/commit/3eb2791c3e9695f7d37ffe84e0c2184fae665cb6 PatchThird Party Advisory
https://huntr.dev/bounties/5f48dac5-e112-4b23-bbbf-cc00ba83bcf2 ExploitThird Party Advisory
https://blog.zulip.com/2022/01/19/cve-2021-3866/ Vendor Advisory
https://github.com/zulip/zulip/commit/3eb2791c3e9695f7d37ffe84e0c2184fae665cb6 PatchThird Party Advisory
https://huntr.dev/bounties/5f48dac5-e112-4b23-bbbf-cc00ba83bcf2 ExploitThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2021-3866), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.