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Fencer Vulns
medium 5.4

CVE-2023-37658 json

fast-poster v2.15.0 is vulnerable to Cross Site Scripting (XSS).

published 2023-07-11 3 y ago modified 2026-06-17 4 mo ago also EUVD-2023-41537

cvss
5.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 32%
public exploits
0
none known

Summary

fast-poster v2.15.0 is vulnerable to Cross Site Scripting (XSS). File upload check binary of img, but without strictly check file suffix at /server/fast.py -> ApiUploadHandler.post causes stored XSS

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
2 y ago

Exploit prediction

0.38% chance of exploitation in the next 30 days, higher than 32% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/psoho/fast-poster/issues/13 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

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.