Cross-site Scripting (XSS) - Stored in zulip/zulip

published 2022-01-20 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-27101

cvss: 6.8; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.9%; EPSS 0.9% chance of exploitation in 30 days, percentile 59%
public exploits: 0; none known

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

Patch / fix

fixed in 1 links 1

zulip zulip/zulip 3eb2791c3e9695f7d37ffe84e0c2184fae665cb6

github.com/zulip/zulip@3eb2791 commit

Exploit prediction

0.89% chance of exploitation in the next 30 days, higher than 59% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

huntr.dev https://huntr.dev/bounties/5f48dac5-e112-4b23-bbbf-cc00ba83bcf2 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
CNA	3.0	6.8	CVSS:3.0/AV:N/AC:H/PR:H/UI:R/S:C/C:H/I:L/A:L
NVD	3.1	5.4	CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD	2.0	3.5	AV:N/AC:M/Au:S/C:N/I:P/A:N

Affected products

zulip zulip/zulip

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

github.com /zulip/zulip/commit/3eb2791c3e9695f7d37ffe84e0c2184fae665cb6
patch, third-party-advisory
huntr.dev /bounties/5f48dac5-e112-4b23-bbbf-cc00ba83bcf2
exploit, third-party-advisory
blog.zulip.com /2022/01/19/cve-2021-3866/
vendor-advisory

Sources

CVE List CVE-2021-3866
NVD CVE-2021-3866

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary