CVE-2021-37859 json
Reflected XSS in OAuth Flow
published 2021-08-05 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-24338
- cvss
- 7.1
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 3.3%
- EPSS 3.3% chance of exploitation in 30 days, percentile 88%
- public exploits
- 0
- none known
Summary
Fixed a bypass for a reflected cross-site scripting vulnerability affecting OAuth-enabled instances of Mattermost.
Patch / fix
- Mattermost Mattermost 5.34.5, 5.35.4
Exploit prediction
3.29% chance of exploitation in the next 30 days, higher than 88% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:L |
| NVD | 3.1 | 6.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| NVD | 2.0 | 4.3 | AV:N/AC:M/Au:N/C:N/I:P/A:N |
Affected products
- Mattermost Mattermost
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
mattermost.com
/security-updates/
vendor-advisory
Sources
- CVE List CVE-2021-37859
- NVD CVE-2021-37859
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.