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CVE-2026-43178: procfs: fix possible double mmput() in do_procmap_query()

• Severity: high (CVSS 7.8 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: 2026-05-06 · updated 2026-07-15
• Weakness: CWE-415

Description

In the Linux kernel, the following vulnerability has been resolved: procfs: fix possible double mmput() in do_procmap_query() When user provides incorrectly sized buffer for build ID for PROCMAP_QUERY we return with -ENAMETOOLONG error. After recent changes this condition happens later, after we unlocked mmap_lock/per-VMA lock and did mmput(), so original goto out is now wrong and will double-mmput() mm_struct. Fix by jumping further to clean up only vm_file and name_buf.

Affected products

• Linux kernel: from 6.12.70 before 6.12.75; from 6.18.10 before 6.18.16; from 6.19.1 before 6.19.6; 6.19 — fixed in 6.12.75, 6.18.16, 6.19.6

How to fix

Upgrade to a fixed version: Linux kernel 6.12.75, 6.18.16, 6.19.6. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/61dc9f776705d6db6847c101b98fa4f0e9eb6fa3
• https://git.kernel.org/stable/c/8adaff87db143583e08eec4f4e7788f1ef8af94d
• https://git.kernel.org/stable/c/90f5e87c9b75833b9ef3a4415b92c0247f28ab2f
• https://git.kernel.org/stable/c/f9fe092084cd04deea18747f58a2304026e76aaa
• https://access.redhat.com/security/cve/CVE-2026-43178
• https://bugzilla.redhat.com/show_bug.cgi?id=2467227
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43178.json

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