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Fencer Vulns
high 7.6

CVE-2025-53528 json

Cadwyn is vulnerable to an XSS attack through its docs page

published 2025-07-21 15 mo ago modified 2026-06-17 4 mo ago also GHSA-2gxp-6r36-m97r , PYSEC-2025-71 , EUVD-2025-22154

cvss
7.6
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 20%
public exploits
0
none known

Summary

Cadwyn creates production-ready community-driven modern Stripe-like API versioning in FastAPI. In versions before 5.4.3, the version parameter of the "/docs" endpoint is vulnerable to a Reflected XSS (Cross-Site Scripting) attack. This XSS would notably allow an attacker to execute JavaScript code on a user's session for any application based on Cadwyn via a one-click attack. The vulnerability has been fixed in version 5.4.3.

Patch / fix

  • pypi cadwyn 5.4.3

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
15 mo ago

Exploit prediction

0.28% chance of exploitation in the next 30 days, higher than 20% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 7.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:L
GitHub 3.1 7.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:L

Affected packages

ecosystem package affected fixed in
pypi cadwyn
<5.4.3
5.4.3

Affected products

  • zmievsa cadwyn

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

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.