Unsafe Deserialization in october/system (CVE-2026-49400)
Summary
Vulnerability in october/system (CVE-2026-49400). Risk of unauthorized operations or information disclosure. Exploitable via SessionMaker. Mitigation: upgrade to 3.7.17 or later.
Original description
The description as published by the source.
The backend SessionMaker trait stored widget session state as base64(serialize(...)) and consumed it with unserialize() without an allowed_classes restriction. Any code path that could write to a widget.* session key with attacker-controlled bytes could trigger PHP object injection the next time the widget read its session state, allowing instantiation of arbitrary classes and reachable PHP gadget chains.
This issue only affects installations running with cms.safe_mode enabled. Safe Mode is a niche opt-in feature, primarily used for demo installations and multi-tenant or shared-editor scenarios where untrusted users are deliberately granted access to the CMS markup editor. In standard production deployments Safe Mode is off, backend access is restricted to trusted administrators, and a markup editor can already execute arbitrary PHP directly. The session-write path that reaches this sink is gated by the Safe Mode sandbox, so installations without Safe Mode enabled are not exposed.
Scope of impact is narrow even with Safe Mode enabled. The standard backend code paths that populate widget session state (search terms, sort options, selected IDs, filter values) wrap the input inside a known array shape before serializing, so user-supplied values never reach unserialize() as a controllable serialized payload. Exploitation requires the Safe Mode session-write path together with a suitable PHP gadget chain reachable from the installed dependency set. The hard…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-49400 has been found in october/system.
Attackers can target a specific entry point like SessionMaker over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 3.3/10.
What to do: upgrade october/system to 3.7.17 or later.
If unsure, ask your IT team or search "october/system CVE-2026-49400" on the vendor's site.
CVE-2026-49400 (october/system) — CWE-502 / CVSS v3 3.3
Attack vector: remote (network-reachable) / no user interaction
Attack surface: SessionMaker / allowed_classes / cms.safe_mode
Patched: 3.7.17 — apply immediately
Workaround: If upgrading immediately is not possible, restrict CMS markup editing access to fully trusted administrators only, the standard October CMS recommendation for any deployment.
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
Unsafe deserialization (CWE-502) exists in october/system. Attackers reach the vulnerable code path via SessionMaker.
Check the vendor advisory for the affected versions of october/system. Attack surface: SessionMaker / allowed_classes / cms.safe_mode.
Severity: Low (CVSS 3.3/10). Risk of unauthorized operations or information disclosure.
Update to 3.7.17.
Workaround: If upgrading immediately is not possible, restrict CMS markup editing access to fully trusted administrators only, the standard October CMS recommendation for any deployment.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'october/system' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'october/system' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
october/systemを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
If upgrading immediately is not possible, restrict CMS markup editing access to fully trusted administrators only, the standard October CMS recommendation for any deployment.パッチが適用されるまでの応急処置として、If upgrading immediately is not possible, restrict CMS markup editing access to fully trusted administrators only, the standard October CMS recommendation for any deployment. を実施。回避策の副作用 (機能低下) を確認した上で。
-
3Apply patch patch
Upgrade october/system to 3.7.17ステージング環境で 3.7.17 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
4Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- web github.com
- web github.com