# CVE-2026-72193: ntfs3: cap RESTART_TABLE free-chain walker at rt->used

Status: published. Published: 2026-08-15. Updated: 2026-11-06.

In the Linux kernel, the following vulnerability has been resolved:

ntfs3: cap RESTART_TABLE free-chain walker at rt->used

A crafted NTFS3 disk image triggers an in-kernel infinite loop at
mount time, hanging the mounting thread and firing the soft-lockup
watchdog within ~22s on multi-CPU hosts (panic with
kernel.softlockup_panic=1).  The bug is reachable from desktop USB
auto-mount on distributions where udisks2 routes the NTFS signature
to the in-tree ntfs3 driver (Arch family and an increasing fraction
of Fedora / openSUSE / RHEL deployments); CAP_SYS_ADMIN-class manual
mount elsewhere.

check_rstbl()'s second walker iterates the free-entry singly-linked
list headed by rt->first_free with no upper bound on iteration count:

  for (off = ff; off;) {
      if (off == RESTART_ENTRY_ALLOCATED)
          return false;
      off = le32_to_cpu(*(__le32 *)Add2Ptr(rt, off));
      if (off > ts - sizeof(__le32))
          return false;
  }

The existing guards cover three exits: end-of-list (off == 0), the
in-use marker (off == RESTART_ENTRY_ALLOCATED), and out-of-bounds
(off > ts - sizeof(__le32)).  None of the three prevents an
in-bounds cycle.

A crafted on-disk RESTART_TABLE whose free chain contains a
self-loop or A->B->A cycle whose offsets satisfy:

  - in range [sizeof(struct RESTART_TABLE), ts - sizeof(__le32)]
  - (off - sizeof(struct RESTART_TABLE)) % rsize == 0

passes all existing guards and spins the mount-time thread forever.
Reproduced in UML by hand-forging a 2 MB NTFS3 image whose journal
RESTART_TABLE first_free = 0x18 and whose entry at offset 0x18
stores 0x18 as its next pointer; mount of the forged image with
the in-tree ntfs3 driver never returns.

Bound the walker by rt->used.  Each entry on a legitimate free
chain is unique, and the total slot count is ne = le16_to_cpu
(rt->used).  A traversal that visits more than ne slots is by
construction malformed; reject it as a corrupt RESTART_TABLE.

After this patch, mount of the forged image returns with -EINVAL
and a log_replay failure message, and mkntfs-produced legitimate
images mount cleanly (verified in the same UML harness).

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ b46acd6a6a627d876898e1c84d3f84902264b445; < 8128bec895075253c779d67afdc90ae513265fca (affected, git); ≥ b46acd6a6a627d876898e1c84d3f84902264b445; < 7972df425687daa70d971fe6ed415e78683133dd (affected, git); ≥ b46acd6a6a627d876898e1c84d3f84902264b445; < 7ac4c86915c24c208a0f0611b71d9676686fe756 (affected, git); ≥ b46acd6a6a627d876898e1c84d3f84902264b445; < 29b86dbe88cbbef53bb9aaec2e279359f8c450f8 (affected, git); ≥ b46acd6a6a627d876898e1c84d3f84902264b445; < 0fad25687d4d3fa1fdd313d31b9cb5817c425029 (affected, git); ≥ b46acd6a6a627d876898e1c84d3f84902264b445; < d313416280d41bea272f02a6034dfa88008692a0 (affected, git); ≥ b46acd6a6a627d876898e1c84d3f84902264b445; < 9611f644302c07d21bc8af97e3e06a3d30064253 (affected, git). Source: CNA: Linux
- Linux / Linux: 5.15 (affected); ≥ 0; < 5.15 (unaffected, semver); ≥ 5.15.212; ≤ 5.15.* (unaffected, semver); ≥ 6.1.178; ≤ 6.1.* (unaffected, semver); ≥ 6.6.145; ≤ 6.6.* (unaffected, semver); ≥ 6.12.97; ≤ 6.12.* (unaffected, semver); ≥ 6.18.40; ≤ 6.18.* (unaffected, semver); ≥ 7.1.5; ≤ 7.1.* (unaffected, semver); ≥ 7.2; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.21% as of 2026-11-06; percentile 11.91%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/8128bec895075253c779d67afdc90ae513265fca (CNA: Linux)

- https://git.kernel.org/stable/c/7972df425687daa70d971fe6ed415e78683133dd (CNA: Linux)

- https://git.kernel.org/stable/c/7ac4c86915c24c208a0f0611b71d9676686fe756 (CNA: Linux)

- https://git.kernel.org/stable/c/29b86dbe88cbbef53bb9aaec2e279359f8c450f8 (CNA: Linux)

- https://git.kernel.org/stable/c/0fad25687d4d3fa1fdd313d31b9cb5817c425029 (CNA: Linux)

- https://git.kernel.org/stable/c/d313416280d41bea272f02a6034dfa88008692a0 (CNA: Linux)

- https://git.kernel.org/stable/c/9611f644302c07d21bc8af97e3e06a3d30064253 (CNA: Linux)

- https://git.kernel.org/stable/c/0fad25687d4d3fa1fdd313d31b9cb5817c425029 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/29b86dbe88cbbef53bb9aaec2e279359f8c450f8 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/7972df425687daa70d971fe6ed415e78683133dd (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/7ac4c86915c24c208a0f0611b71d9676686fe756 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/8128bec895075253c779d67afdc90ae513265fca (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/9611f644302c07d21bc8af97e3e06a3d30064253 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

- https://git.kernel.org/stable/c/d313416280d41bea272f02a6034dfa88008692a0 (416baaa9-dc9f-4396-8d5f-8c081fb06d67)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2026-72193; retrieved 2026-11-06; source updated 2026-11-06

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-72193; retrieved 2026-11-06; source updated 2026-11-06

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-72193; retrieved 2026-11-06; source updated Not reported

Revision: 9a20aa1efee63aeec0b3695e9ba63923df8aec23700aa25a46bd332e298e9fbd

Canonical: https://y2.dev/cve/CVE-2026-72193

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