Promptcraft Forge Studio: Complete Sanitizer Bypass Enables XSS via Overlapping Patterns

published 2025-09-04 14 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-26866

cvss: 8.2; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 15%
public exploits: 0; none known

Promptcraft Forge Studio is a toolkit for evaluating, optimizing, and maintaining LLM-powered applications. All versions of Promptcraft Forge Studio sanitize user input using regex blacklists such as r`eplace(/javascript:/gi, '')`. Because the package uses multi-character tokens and each replacement is applied only once, removing one occurrence can create a new dangerous token due to overlap. The “sanitized” value may still contain an executable payload when used in href/src (or injected into the DOM). There is currently no fix for this issue.

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 14 mo ago (2025-09-04)

Exploit prediction

0.24% chance of exploitation in the next 30 days, higher than 15% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	8.2	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

Affected products

MarceloTessaro promptcraft-forge-studio

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation
CWE-20 Improper Input Validation
CWE-184 Incomplete List of Disallowed Inputs

References

github.com /MarceloTessaro/promptcraft-forge-studio/security/advisories/GHSA-mv25-7v95-q3pf

Sources

CVE List CVE-2025-58353
NVD CVE-2025-58353

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