CVE-2026-72433 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nft_meta_bridge: fix NFT_META_BRI_IIFPVID stack leak
This needs to test for nonzero retval.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability identified in the Linux kernel's netfilter subsystem represents a critical stack memory leak scenario affecting the nft_meta_bridge module. This flaw manifests within the handling of NFT_META_BRI_IIFPVID operations, where the system fails to properly validate return values from underlying functions. The issue stems from inadequate error checking mechanisms that should verify whether the returned value from kernel operations is nonzero before proceeding with subsequent processing. When such validation is omitted, the system may continue execution with uninitialized or corrupted stack memory contents, potentially leading to information disclosure or system instability.
The technical implementation flaw resides in the nft_meta_bridge component of the netfilter framework, specifically within how it processes bridge interface metadata operations. The NFT_META_BRI_IIFPVID constant refers to a netfilter table operation that retrieves the port VLAN ID from incoming interface packets. When the underlying kernel function fails to return an expected nonzero value, the calling code continues execution without proper error handling, allowing stack memory containing sensitive data or uninitialized values to persist in memory space. This represents a classic stack-based memory leak vulnerability where corrupted stack contents are not properly sanitized before reuse.
This vulnerability impacts systems running Linux kernels with netfilter functionality enabled, particularly those utilizing bridge networking configurations and packet filtering rules. The operational consequences include potential information leakage through memory corruption artifacts that may be accessible to local attackers or processes running in the same security context. The stack leak could expose kernel memory contents including sensitive data structures, cryptographic keys, or other confidential information stored within the kernel's memory space. Additionally, the persistence of corrupted stack values might lead to unpredictable system behavior or facilitate more sophisticated attacks targeting kernel memory management.
Security mitigation strategies should focus on implementing proper return value validation throughout the nft_meta_bridge processing pipeline. The fix requires adding explicit nonzero checks for all function return codes before proceeding with data manipulation operations. System administrators should prioritize kernel updates containing the patched netfilter implementation, which typically follows established security protocols and vulnerability disclosure practices. Organizations utilizing bridge networking configurations or complex packet filtering rules must conduct thorough testing to ensure that updated kernels maintain compatibility while eliminating the memory leak conditions. The vulnerability aligns with CWE-457: Use of Uninitialized Variable and ATT&CK technique T1068: Exploitation for Privilege Escalation, as improper error handling can create pathways for attackers to extract sensitive information from kernel memory spaces through memory corruption artifacts.
The fix implementation specifically addresses the missing validation check by ensuring that any nonzero return value from underlying operations triggers appropriate error handling or early termination of processing. This approach aligns with secure coding practices recommended in the Linux kernel security guidelines and follows industry standards for preventing information disclosure vulnerabilities. The resolution demonstrates proper defensive programming where all potential failure points within kernel subsystems are explicitly checked and handled according to established security protocols, thereby reducing the attack surface and preventing unauthorized access to kernel memory contents through stack-based information leakage mechanisms.