Discourse Placeholder Forms has a XSS stopped by CSP

published 2024-08-20 2 y ago modified 2026-06-17 4 mo ago also EUVD-2024-40270

cvss: 6.3; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 17%
public exploits: 0; none known

Discourse Placeholder Forms will let you build dynamic documentation. Unsanitized and stored user input was injected in the html of the post. The vulnerability is fixed in commit a62f711d5600e4e5d86f342d52932cb6221672e7.

Patch / fix

links 1

github.com/discourse/discourse-placeholder-theme-component@a62f711 commit

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 2 y ago (2024-08-21)

Exploit prediction

0.26% chance of exploitation in the next 30 days, higher than 17% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.3	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L

Affected products

discourse discourse-placeholder-theme-component

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

CVE List CVE-2024-43408
NVD CVE-2024-43408

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