8.1

CVE-2026-91827: unknown ninja forms Deserialization of Untrusted Data

CVSS: 8.1v3.1HighDeferred
Published 22-09-2026Last modified 22-09-2026
Open JSON

Vulnerability summary

CVE-2026-91827 is a high (CVSS 8.1) Deserialization of Untrusted Data vulnerability in unknown ninja forms. EPSS estimates a 0.30% chance of exploitation in the next 30 days, higher than 21.7% of scored vulnerabilities. 1 public exploit is recorded. Fixed in 3.15.4.

Overall risk
42/100
0100
Medium · default modelHow is this calculated?
CVSS score
8.1/10
010
High · v3.1 (wordfence)
EPSS score
0.30%
0%100%
Low · Change unavailable
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1reference

Timeline

  1. 22-09-2026
    PublishedVulnerability first disclosed.
  2. 22-09-2026
    Last modifiedVulnerability information updated.

Description

The Ninja Forms WordPress plugin 3.15.3 does not prevent user-submitted form field values from being deserialised when an administrator later exports form submissions to CSV, allowing unauthenticated attackers to perform PHP Object Injection; if a suitable POP chain is present via another installed plugin or theme, this can lead to actions such as arbitrary file operations or remote code execution.

CVSS metrics

3 scores · 3 sources · 1 version

EPSS trend

Probability

0.30%

Chance of exploitation in the next 30 days

Percentile

22%

Versus all other CVEs

30-day change

Change unavailable

Change unavailable

22-09-202618-10-2026
EPSS score
0.30%

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
  • ninja-forms≤ 3.15.3 (fixed in 3.15.4)

2 vendors · 2 products

References

2 links