CyberSecBulletin
CVE-2026-8727NVD status: Deferred

Extension "Site Crawler": Deserialization of Untrusted Data

Published Updated By the CyberSecBulletin desk

CVE-2026-8727 is a high-severity deserialization of untrusted data vulnerability in Extension "Site Crawler" from TYPO3, with a CVSS 4.0 base score of 7.1 out of 10. It can be exploited remotely over the network by an attacker with administrator privileges, but only if a user takes part, for example by opening a link or file. The record lists versions 12.0.11, 11.0.13 as the first without the flaw, so updating Extension "Site Crawler" to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.39% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Extension "Site Crawler" to 12.0.11 or 11.0.13, whichever matches your release line, or a later version.
  2. Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.

Affected products and versions

VendorProductAffected versionsFixed in
TYPO3Extension "Site Crawler"12.0.0 up to, but not including, 12.0.11; before 11.0.1312.0.11, 11.0.13

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Attack requirements
PresentThe target must be in a specific state or configuration for the attack to work.
Privileges required
HighAdministrator-level access is required first.
User interaction
ActiveA user must deliberately do something unusual, such as dismissing a warning.
Confidentiality (vulnerable system)
HighSerious loss of confidentiality on the vulnerable system.
Integrity (vulnerable system)
HighSerious loss of integrity on the vulnerable system.
Availability (vulnerable system)
HighSerious loss of availability on the vulnerable system.
Confidentiality (other systems)
LowLimited loss of confidentiality on systems beyond the vulnerable one.
Integrity (other systems)
LowLimited loss of integrity on systems beyond the vulnerable one.
Availability (other systems)
LowLimited loss of availability on systems beyond the vulnerable one.

Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:A/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/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. Scored by CNA.

Official description

The Crawler extension passes the X-T3Crawler-Meta response header from crawled URLs directly to PHP's unserialize(). An attacker controlling a crawled endpoint can inject arbitrary serialized PHP objects, leading to Remote Code Execution on the TYPO3 server. Exploitation requires administrative privileges to configure a crawler-enabled page and trigger the crawl via a Scheduler task.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Deserialization of Untrusted Data

The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.

How developers prevent this class of flaw

  • If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
  • When deserializing data, populate a new object rather than just deserializing. The result is that the data flows through safe input validation and that the functions are safe.
  • Explicitly define a final object() to prevent deserialization.

More Deserialization of Untrusted Data vulnerabilities (CWE-502)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Deserialization of Untrusted Data vulnerabilities

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