CVE-2026-40706

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.

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CVSS v3.1 Score

8.4

HIGH

CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS — Exploit Prediction

0.0002

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-122 CWE-122

References

Other References

https://github.com/tuxera/ntfs-3g/blob/d3ace19838ce37cfde55294e76841e6d2f393f9e/libntfs-3g/acls.c#L4011-L4027 https://github.com/tuxera/ntfs-3g/releases/tag/2026.2.25 https://github.com/tuxera/ntfs-3g/security/advisories/GHSA-4cwv-5285-63v9 https://www.openwall.com/lists/oss-security/2026/04/21/4 http://www.openwall.com/lists/oss-security/2026/04/21/4 https://lists.debian.org/debian-lts-announce/2026/04/msg00024.html

Frequently Asked Questions

What is 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 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. It has a CVSS v3.1 base score of 8.4 (HIGH).

How severe is CVE-2026-40706? +

CVE-2026-40706 has a CVSS v3.1 score of 8.4 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0002, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-40706? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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