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Fencer Vulns
medium 6.1

CVE-2021-33557 json

MantisBT allows XSS in manage_custom_field_edit_page.php

published 2021-06-17 5 y ago modified 2026-06-17 4 mo ago also GHSA-52cx-vphc-jmjm , EUVD-2021-20249

cvss
6.1
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.8%
EPSS 1.8% chance of exploitation in 30 days, percentile 78%
public exploits
0
none known

Summary

An XSS issue was discovered in manage_custom_field_edit_page.php in MantisBT before 2.25.2. Unescaped output of the return parameter allows an attacker to inject code into a hidden input field.

Patch / fix

  • packagist mantisbt/mantisbt 2.25.2
  • mantisbt mantisbt 2.25.2

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-33557 updated cvss 8.8

mantis: An XSS issue was discovered in manage_custom_field_edit_page.php which allows an attacker to inject code into a hidden input field.

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.82% chance of exploitation in the next 30 days, higher than 78% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • mantisbt.org https://mantisbt.org/bugs/view.php?id=28552 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:N/I:P/A:N
GitHub 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected packages

ecosystem package affected fixed in
packagist mantisbt/mantisbt
<2.25.2
2.25.2

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.