CVE-2021-39161 json
Cross-site scripting via category name in Discourse
published 5y ago modified 2mo ago also BIT-discourse-2021-39161 , EUVD-2021-25570 , GHSA-xhmc-9jwm-wqph
- cvss
- 4.4
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.4%
- EPSS 0.4% chance of exploitation in 30 days, percentile 35%
- public exploits
- 0
- none known
Summary
Discourse is an open source platform for community discussion. In affected versions category names can be used for Cross-site scripting(XSS) attacks. This is mitigated by Discourse's default Content Security Policy and this vulnerability only affects sites which have modified or disabled or changed Discourse's default Content Security Policy have allowed for moderators to modify categories. This issue is patched in the latest stable, beta and tests-passed versions of Discourse. Users are advised to ensure that the Content Security Policy is enabled, and has not been modified in a way which would make it more vulnerable to XSS attacks.
Patch / fix
- bitnami discourse 2.7.8
- discourse discourse 2.7.8
Is CVE-2021-39161 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerExploit prediction
0.41% chance of exploitation in the next 30 days, higher than 35% of all scored CVEs (FIRST EPSS, 2026-11-09).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 4.4 | CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:N |
| 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 | 2.1 | AV:N/AC:H/Au:S/C:N/I:P/A:N |
| OSV | 3.1 | 5.4 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| bitnami | discourse | <2.7.8 |
2.7.8 |
Affected products
- discourse discourse
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
-
github.com
/discourse/discourse/security/advisories/GHSA-xhmc-9jwm-wqph
third-party-advisory, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2021-39161
web
Sources
- CVE List CVE-2021-39161
- NVD CVE-2021-39161
- OSV BIT-discourse-2021-39161
Fencer Intel 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.