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Fencer Intel
high 8.7

CVE-2019-12830 json

In MyBB before 1.8.21, an attacker can exploit a parsing flaw in the Private Message / Post renderer that leads to [video] BBCode persisten…

published 7y ago modified 4mo ago also EUVD-2019-4410

cvss
8.7
version 3.0, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 61%
public exploits
0
none known

Summary

In MyBB before 1.8.21, an attacker can exploit a parsing flaw in the Private Message / Post renderer that leads to [video] BBCode persistent XSS to take over any forum account, aka a nested video MyCode issue.

Patch / fix

  • mybb mybb 1.8.21

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Exploit prediction

0.96% chance of exploitation in the next 30 days, higher than 61% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • blog.ripstech.com https://blog.ripstech.com/2019/mybb-stored-xss-to-rce/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.0 8.7 CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
NVD 2.0 3.5 AV:N/AC:M/Au:S/C:N/I:P/A:N

Classification

Weakness
  • 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.