9.9

CVE-2026-82845: unknown masteriyo lms Deserialization of Untrusted Data

CVSS: 9.9v3.1CriticalDeferred
Published 12-09-2026Last modified 12-09-2026
Open JSON

Vulnerability summary

CVE-2026-82845 is a critical (CVSS 9.9) Deserialization of Untrusted Data vulnerability in unknown masteriyo lms. EPSS estimates a 0.64% chance of exploitation in the next 30 days, higher than 49.5% of scored vulnerabilities. 1 public exploit is recorded. Fixed in 3.4.1.

Overall risk
70/100
0100
High · default modelHow is this calculated?
CVSS score
9.9/10
010
Critical · v3.1 (CVE.org)
EPSS score
0.64%
0%100%
Low · +0.28 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1reference

Timeline

  1. 12-09-2026
    PublishedVulnerability first disclosed.
  2. 12-09-2026
    Last modifiedVulnerability information updated.

Description

The Masteriyo LMS WordPress plugin before 3.4.1 does not prevent user-supplied values held as metadata from being deserialized when they are read back, allowing users with a minimal account to inject arbitrary PHP objects and, by way of a class shipped in a library bundled with the Masteriyo LMS WordPress plugin before 3.4.1, write and execute arbitrary code on the server. A weaker form of the same issue is reachable without an account and yields an arbitrary file write rather than code execution.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.64%

Chance of exploitation in the next 30 days

Percentile

50%

Versus all other CVEs

30-day change

+0.28 pp

From 0.35% on 19-09-2026

19-09-202619-10-2026
EPSS score
0.64%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • referenceUnverified

    Exploit Reference (wpscan.com)

    Maturity: unknown

Weaknesses

CWE · root cause

Affected systems

Unknown1 product
Wordpress1 product
  • learning-management-system≤ 3.4.0 (fixed in 3.4.1)

2 vendors · 2 products

References

2 links