Bug 2535080 (CVE-2026-89779)

Summary: CVE-2026-89779 kernel: fs/ntfs3: validate ef->size covers the record's name and value
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in the Linux kernel's ntfs3 filesystem driver. This vulnerability allows a local attacker to craft an Extended Attribute (EA) record with an undersized ef->size value. When processed, this can lead to an out-of-bounds read, resulting in the disclosure of sensitive heap memory to userspace. This information disclosure could potentially expose confidential system data.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Description OSIDB Bzimport 2026-09-16 09:14:42 UTC 
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.
Comment 1 Keith Grant 2026-09-21 19:21:47 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-89779.mbox