CVE-2024-12878 json
Custom Block Builder – Lazy Blocks < 3.8.3 - Reflected XSS
published 2025-02-26 20 mo ago modified 2026-06-17 4 mo ago also EUVD-2025-5312
- cvss
- 7.1
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.6%
- EPSS 0.6% chance of exploitation in 30 days, percentile 49%
- public exploits
- 0
- none known, plus a Nuclei check
Summary
The Custom Block Builder WordPress plugin before 3.8.3 does not sanitise and escape a parameter before outputting it back in the page, leading to a Reflected Cross-Site Scripting which could be used against high privilege users such as admin.
Patch / fix
- Unknown Custom Block Builder 3.8.3
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 20 mo ago
Exploit prediction
0.62% chance of exploitation in the next 30 days, higher than 49% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- Nuclei template Lazy Blocks <= 3.8.2 - Cross-Site Scripting nuclei detection template
- wpscan.com https://wpscan.com/vulnerability/827444d1-87cb-4057-827a-d802eac82cf8/ 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 Custom Block Builder
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
- Technology feeds
References
-
wpscan.com
/vulnerability/827444d1-87cb-4057-827a-d802eac82cf8/
exploit, vdb-entry, technical-description, third-party-advisory
Sources
- CVE List CVE-2024-12878
- NVD CVE-2024-12878
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.