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Deserialization of Untrusted DataWeakness · CWE-502

CVE-2026-49740

MEDIUM · 6.3 CVSS v4.0 Published 2026-06-09
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
65/100
Remediation priority · Elevated
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
TYPO3's cache frontend (VariableFrontend) and persistent key-value store (Registry) deserialized PHP payloads without integrity validation or class restrictions. An attacker with write access to the underlying storage backend (cache store or sys_registry database table) could inject a crafted serialized payload to trigger PHP Object Injection, potentially exploiting a gadget chain to achieve Remote Code Execution or other high-impact effects. Exploiting this vulnerability requires direct local write access to the storage, such as the SQL database or file system. This issue affects TYPO3 CMS versions before 10.4.57, 11.0.0-11.5.50, 12.0.0-12.4.45, 13.0.0-13.4.30 and 14.0.0-14.3.2.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-502

The application rebuilds objects from attacker-supplied serialized data, and the act of rebuilding can trigger dangerous code paths. In many runtimes this leads straight to remote code execution. The durable fix is to avoid deserializing untrusted input — or to use a strict, type-limited format with integrity checks.

General guidance for the deserialization of untrusted data class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
Authentication
X
User interaction
None
Scope
X

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:H/SI:H/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Recommended fix High confidence

Upgrade to the next minor version in your current branch: 10.4.57, 11.5.51, 12.4.46, 13.4.31, or 14.3.3 (whichever applies)

  1. 1. Identify the currently installed TYPO3 CMS version by checking the composer.json or system information in the TYPO3 backend.
  2. 2. For TYPO3 versions below 10.4.57: Upgrade to version 10.4.57 or later.
  3. 3. For TYPO3 versions 11.0.0-11.5.50: Upgrade to version 11.5.51 or later.
  4. 4. For TYPO3 versions 12.0.0-12.4.45: Upgrade to version 12.4.46 or later.
  5. 5. For TYPO3 versions 13.0.0-13.4.30: Upgrade to version 13.4.31 or later.
  6. 6. For TYPO3 versions 14.0.0-14.3.2: Upgrade to version 14.3.3 or later.
  7. 7. After upgrading, verify the installation works correctly and clear all caches via the Install Tool or CLI: typo3cms cache:flush.
Caveat Review TYPO3 release notes for your upgrade path; major version jumps may require code adjustments for deprecated APIs

Generated from the published advisory — verify against the referenced sources before acting.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-49740 in production — separate from our analysis above.

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