CVE-2024-50251 in Linux
Summary
by MITRE • 11/09/2024
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nft_payload: sanitize offset and length before calling skb_checksum()
If access to offset + length is larger than the skbuff length, then skb_checksum() triggers BUG_ON().
skb_checksum() internally subtracts the length parameter while iterating over skbuff, BUG_ON(len) at the end of it checks that the expected length to be included in the checksum calculation is fully consumed.
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Analysis
by VulDB Data Team • 07/16/2025
The vulnerability identified as CVE-2024-50251 resides within the Linux kernel's netfilter subsystem, specifically affecting the nft_payload functionality. This issue represents a critical flaw in the handling of packet checksum calculations that could lead to system instability and potential denial of service conditions. The vulnerability manifests when the netfilter framework processes network packets through the nft_payload expression, which is commonly used in nftables for payload manipulation and inspection. The flaw occurs during the validation of packet data access parameters before checksum computation, creating a scenario where improper boundary checking can trigger kernel panics.
The technical root cause of this vulnerability stems from inadequate validation of offset and length parameters before invoking the skb_checksum() function. When the calculated access range defined by offset plus length exceeds the actual skbuff length, the skb_checksum() function encounters a critical condition that triggers a BUG_ON() macro. This kernel debugging mechanism is designed to catch programming errors by asserting that certain conditions must always be true. The internal implementation of skb_checksum() performs iterative processing of the skbuff data while maintaining a running count of the remaining length to be processed. When the function completes its iteration, it performs a final validation check through BUG_ON(len) to ensure that the expected length has been fully consumed, which fails when the boundary parameters are invalid.
The operational impact of this vulnerability extends beyond simple system crashes, potentially enabling attackers to craft malicious network packets that can trigger kernel panics and system reboots. This type of vulnerability falls under the Common Weakness Enumeration category CWE-129, which addresses improper validation of array indices and buffer overflows. The attack surface is particularly concerning as it affects the fundamental packet processing capabilities of the Linux kernel, potentially impacting network services, firewalls, and security appliances that rely heavily on netfilter and nftables. Systems running kernel versions containing this vulnerability may experience denial of service conditions where legitimate network traffic processing is interrupted, leading to service unavailability and potential data loss.
Mitigation strategies for CVE-2024-50251 should prioritize immediate kernel updates from trusted sources, as the vulnerability has been resolved in recent kernel releases. Network administrators should also implement robust monitoring systems to detect unusual patterns of kernel panics or system reboots that might indicate exploitation attempts. The fix implemented in the kernel involves adding proper bounds checking before calling skb_checksum(), ensuring that the offset plus length parameters do not exceed the skbuff boundaries. This remediation aligns with the ATT&CK framework's defense evasion techniques, specifically addressing the potential for kernel-level privilege escalation through malformed packet processing. Organizations should also consider implementing network segmentation and access controls to limit exposure, while maintaining regular security assessments to identify similar vulnerabilities in their network infrastructure components.