CVE-2026-74590
Received Received - Intake

fsverity Memory Corruption in Linux Kernel

Publication date: 2026-08-22

Last updated on: 2026-08-22

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: fsverity: Fix bpf_get_fsverity_digest() dynptr assumptions The BPF verifier and the dynptr abstraction ensure that the memory space referenced by a dynptr remains valid. They do not, however, provide any guarantee that the contents of the memory are stable. kfuncs are expected to remain memory-safe even if concurrent modifications occur. bpf_get_fsverity_digest() didn't follow that: it could crash if arg->digest_size was concurrently modified. Fix that by using the known-good value hash_alg->digest_size instead. Also widen 'dynptr_sz' and 'out_digest_sz' to u64 to match the return type of __bpf_dynptr_size(). It doesn't appear that it can actually be more than INT_MAX currently (since __bpf_dynptr_data_rw() excludes file-based pointers), but the correct type might as well be used.

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Meta Information

Published
2026-08-22
Last Modified
2026-08-22
Generated
2026-08-22
AI Q&A
2026-08-22
EPSS Evaluated
N/A
NVD
CVE-2026-74590
EUVD
EUVD-2026-64527

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

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Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a Linux kernel vulnerability where the BPF verifier's dynptr abstraction fails to ensure memory content stability. The function bpf_get_fsverity_digest() could crash if the digest_size argument was modified concurrently. The fix involves using a known-good value (hash_alg->digest_size) instead.

Detection Guidance

This vulnerability is specific to the Linux kernel's fsverity implementation and BPF verifier. Detection requires checking kernel version and fsverity-related components. Use commands like 'uname -a' to check kernel version and 'lsmod | grep fsverity' to verify if fsverity module is loaded.

Impact Analysis

This vulnerability could cause system crashes or instability if exploited. It primarily affects systems using BPF (Berkeley Packet Filter) with fsverity functionality, potentially leading to denial-of-service conditions.

Mitigation Strategies

Apply the latest kernel patch that fixes this issue. Update your Linux distribution to a version containing the patched kernel. Monitor vendor advisories for specific mitigation steps.

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