CVE-2026-31428
Uninitialized Memory Leak in Linux netfilter NFULA_PAYLOAD
Publication date: 2026-04-13
Last updated on: 2026-04-18
Assigner: kernel.org
Description
Description
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Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| linux | linux_kernel | * |
| linux_kernel | linux_kernel | * |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-UNKNOWN |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in the Linux kernel's netfilter nfnetlink_log component. It involves an uninitialized padding leak in the NFULA_PAYLOAD netlink attribute. Specifically, the function __build_packet_message() manually constructs the NFULA_PAYLOAD attribute by allocating memory for the payload plus padding, but only initializes the actual payload data bytes. The padding bytes, which can be 1 to 3 bytes when the data length is not 4-byte aligned, remain uninitialized and may contain stale heap data. This uninitialized data is then leaked to userspace through the NFLOG netlink socket.
The fix replaces the manual construction with the nla_reserve() helper, which properly initializes the padding bytes to zero, preventing the leakage of stale heap contents.
How can this vulnerability impact me? :
This vulnerability can lead to unintended leakage of kernel heap memory contents to userspace via the NFLOG netlink socket. An attacker or a user with access to this interface could potentially obtain sensitive information from the kernel memory that was not meant to be exposed. This could include data from other processes or kernel structures, potentially leading to information disclosure.
What immediate steps should I take to mitigate this vulnerability?
The vulnerability has been resolved by replacing the manual construction of the NFULA_PAYLOAD netlink attribute with the use of nla_reserve(), which properly initializes padding and prevents leakage of stale heap contents.
Therefore, the immediate step to mitigate this vulnerability is to update the Linux kernel to a version that includes this fix.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
This vulnerability causes uninitialized padding bytes to leak stale heap contents to userspace via the NFLOG netlink socket.
Such leakage of potentially sensitive kernel memory contents could lead to unauthorized disclosure of information.
Unauthorized disclosure of sensitive data may impact compliance with data protection regulations such as GDPR and HIPAA, which require protection of personal and health information.