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Fencer Intel
high 7.1

CVE-2026-121863 json

Knowledge Building < 0.7.3 - Reflected XSS via Comment Reply Response

published yesterday modified 22h ago also EUVD-2026-123187

cvss
7.1
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 12%
public exploits
0
none known

Summary

The Knowledge Building WordPress plugin before 0.7.3 does not escape several user-supplied values before echoing them back in the response of an AJAX action available to unauthenticated users, and serves that response as HTML, leading to a Reflected Cross-Site Scripting.

Patch / fix

  • Unknown Knowledge Building 0.7.3

Is CVE-2026-121863 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
23h ago

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 12% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • wpscan.com https://wpscan.com/vulnerability/80b4b9d0-e48b-4f24-b4bd-71dc37ac1602/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L
CNA 3.1 7.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:L

Affected products

  • Unknown Knowledge Building

Classification

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

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.