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CVE-2026-46182: pseries/papr-hvpipe: Prevent kernel stack memory leak to userspace

• Severity: medium (CVSS 5.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-28 · updated 2026-06-17
• Weakness: CWE-401

Description

In the Linux kernel, the following vulnerability has been resolved: pseries/papr-hvpipe: Prevent kernel stack memory leak to userspace The hdr variable is allocated on the stack and only hdr.version and hdr.flags are initialized explicitly. Because the struct papr_hvpipe_hdr contains reserved padding bytes (reserved[3] and reserved2[40]), these could leak the uninitialized bytes to userspace after copy_to_user(). This patch fixes that by initializing the whole struct to 0.

Affected products

• Linux kernel: from 6.18 before 6.18.30; from 6.19 before 7.0.7; 7.1-rc1, 7.1-rc2 — fixed in 6.18.30, 7.0.7

How to fix

Upgrade to a fixed version: Linux kernel 6.18.30, 7.0.7. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/0479b6e9f999cc1cbad7d9f09f574fc387e605d5
• https://git.kernel.org/stable/c/cefeed44296261173a806bef988b26bc565da4be
• https://git.kernel.org/stable/c/f88f8e4485b437e0a2f96a7ff1f88aa22d925659

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