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Fencer Intel
low 3.5

CVE-2021-4271 json

panicsteve w2wiki Markdown index.php toHTML cross site scripting

published 3y ago modified 4mo ago also EUVD-2021-34113

cvss
3.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 31%
public exploits
0
none known

Summary

A vulnerability was found in panicsteve w2wiki. It has been rated as problematic. Affected by this issue is the function toHTML of the file index.php of the component Markdown Handler. The manipulation leads to cross site scripting. The attack may be launched remotely. The name of the patch is 8f1d0470b4ddb1c7699e3308e765c11ed29542b6. It is recommended to apply a patch to fix this issue. The identifier of this vulnerability is VDB-216476.

Patch / fix

Is CVE-2021-4271 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.37% chance of exploitation in the next 30 days, higher than 31% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 3.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
NVD 3.1 6.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Affected products

  • panicsteve w2wiki

Classification

Weakness
  • CWE-707 Improper Neutralization
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

Fencer Intel 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.