Object injection via widget session deserialization
Published Sep 14, 2026 · Updated Sep 14, 2026
PHP object injection in October CMS before 3.7.17 and 4.0.0 through 4.2.20 allows remote authenticated users to instantiate classes. Backend\Traits\SessionMaker decodes base64 widget state and passes it to unserialize() without blocking class instantiation. Exploitation requires cms.safe_mode, a controllable widget.* session write, and a compatible PHP gadget chain; standard widget writes do not expose raw serialized payloads.
Summary
What happened
PHP object injection in October CMS before 3.7.17 and 4.0.0 through 4.2.20 allows remote authenticated users to instantiate classes. Backend\Traits\SessionMaker decodes base64 widget state and passes it to unserialize() without blocking class instantiation. Exploitation requires cms.safe_mode, a controllable widget.* session write, and a compatible PHP gadget chain; standard widget writes do not expose raw serialized payloads.
The record
- CVE
- CVE-2026-49400
- Published
- Sep 14, 2026
- Updated
- Sep 14, 2026
- Vendor
- October CMS
- Product
- October CMS
- Classifications
- Unavailable
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Sep 14, 2026CVE publishedPublication date reported by the CVE source.
- Sep 14, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 3.7.17
- Affected versionversion=>= 4.0.0, < 4.2.23
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
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Public exploit references
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Technologies
Your stack
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Your stack
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