What’s Vulnerable › Vulnerabilities

CVE-2025-40198: ext4: avoid potential buffer over-read in parse_apply_sb_mount_options()

• Severity: high (CVSS 7.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2025-11-12 · updated 2026-10-19

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: avoid potential buffer over-read in parse_apply_sb_mount_options() Unlike other strings in the ext4 superblock, we rely on tune2fs to make sure s_mount_opts is NUL terminated. Harden parse_apply_sb_mount_options() by treating s_mount_opts as a potential __nonstring.

Affected products

• Linux kernel: 2.6.36 — fixed in 6.18

How to fix

Upgrade to a fixed version: Linux kernel 6.18. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/01829af7656b56d83682b3491265d583d502e502
• https://git.kernel.org/stable/c/2a0cf438320cdb783e0378570744c0ef0d83e934
• https://git.kernel.org/stable/c/7bf46ff83a0ef11836e38ebd72cdc5107209342d
• https://git.kernel.org/stable/c/8ecb790ea8c3fc69e77bace57f14cf0d7c177bd8
• https://git.kernel.org/stable/c/a6e94557cd05adc82fae0400f6e17745563e5412
• https://git.kernel.org/stable/c/b2bac84fde28fb6a88817b8b761abda17a1d300b
• https://git.kernel.org/stable/c/e651294218d2684302ee5ed95ccf381646f3e5b4

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