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Advisory record · GHSA-2ff2-mx52-q8wp

October CMS: PHP Object Injection via Backend Widget Session Storage

CVSS 3.3 LowEPSS 0.0024 · 14th percentile

Published by the GitHub Advisory Database at 14 Sept 2026, 17:08 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

PackageEcosystemAffectedFixed in
october/systemPackagist<3.7.17 || >=4.0.0, <4.2.233.7.17, 4.2.23
Identifiers
GHSA-2ff2-mx52-q8wp · CVE-2026-49400 · PKSA-syjw-hb9p-2d5m
Weakness (CWE)
CWE-502
Tags
Published
14 Sept 2026
Updated
14 Sept 2026

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

October CMS's system package (october/system) versions below 3.7.17, and 4.0.0 through 4.2.22, deserialize widget session data without restricting which classes can be created. Only installations with `cms.safe_mode` enabled are affected. An attacker would need a backend account with CMS markup editing access and a usable PHP gadget chain in the installed dependencies to run arbitrary PHP code as the web server user. Upgrade to 3.7.17 or 4.2.23.

Written 31 Oct 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

ScoreRatingCVSSVectorSource
3.3 Low 3.1 CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:L/A:N CNA (GitHub_M)
  • CISA KEV Not listed.
  • EPSS 0.0024, the 14th percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

  1. 31 Oct 2026, 13:56 UTC First seen by agentprime
  2. 31 Oct 2026, 13:56 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.