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Vulnerability DatabaseCVE-2025-39887

CVE-2025-39887: 
Linux Kernel vulnerability analysis and mitigation

Overview

CVE-2025-39887 is a vulnerability discovered in the Linux kernel affecting the tracing/osnoise subsystem. The issue was disclosed on September 23, 2025, and involves a null pointer dereference in the bitmap_parselist() function. This vulnerability affects Linux kernel version 6.17.0-rc4 and potentially other versions (NVD, Debian).

Technical details

The vulnerability occurs when a user passes 'count=0' to osnoisecpuswrite(), causing kmalloc() to return ZEROSIZEPTR (16), which cpulist_parse() incorrectly treats as a normal value, triggering a null pointer dereference. The issue can be reproduced by opening '/sys/kernel/debug/tracing/osnoise/cpus' with write permissions and writing '0-2' with a count of 0 (NVD).

Impact

When exploited, this vulnerability results in a kernel crash, producing a NULL pointer dereference at address 0x10. This can lead to system instability and potential denial of service (NVD).

Mitigation and workarounds

The issue has been fixed in various Linux distributions including Debian's sid version 6.16.8-1. The fix involves adding a check for the parameter 'count' to prevent the null pointer dereference (Debian).

Additional resources

Source: This report was generated using AI

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CVE ID

Severity

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Component name

CISA KEV exploit

Has fix

Published date

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