CVE-2025-38310 in Linux
Summary
by MITRE • 07/10/2025
In the Linux kernel, the following vulnerability has been resolved:
seg6: Fix validation of nexthop addresses
The kernel currently validates that the length of the provided nexthop address does not exceed the specified length. This can lead to the kernel reading uninitialized memory if user space provided a shorter length than the specified one.
Fix by validating that the provided length exactly matches the specified one.
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Analysis
by VulDB Data Team • 12/19/2025
The vulnerability identified as CVE-2025-38310 resides within the Linux kernel's segment routing over IPv6 implementation, specifically affecting the segment routing6 (seg6) subsystem. This issue manifests in the validation logic for nexthop addresses, which are critical components in determining packet routing paths through complex network topologies. The seg6 functionality enables advanced routing scenarios by allowing packets to traverse multiple nodes in a predetermined path, making it essential for network virtualization and software-defined networking implementations. The vulnerability stems from an inadequate validation mechanism that fails to properly enforce length constraints on nexthop address data structures.
The technical flaw occurs when the kernel processes user-space provided nexthop addresses that contain length specifications shorter than the actual data provided. This discrepancy creates a scenario where the kernel's validation routine only checks if the provided length does not exceed the specified length, rather than enforcing an exact match between the two values. When this condition is met, the kernel proceeds to read memory regions that may contain uninitialized data, potentially exposing sensitive information or creating unpredictable behavior. This type of memory access issue represents a classic case of improper input validation that can lead to information disclosure or system instability. The vulnerability aligns with CWE-129, which addresses issues related to insufficient validation of length fields, and CWE-128, which covers insufficient boundary checking in buffer operations.
The operational impact of this vulnerability extends beyond simple memory access errors, as it could potentially enable attackers to extract uninitialized memory contents from kernel space. This information disclosure could reveal sensitive kernel data structures, cryptographic keys, or other confidential information that might aid in further exploitation attempts. In environments where the seg6 functionality is actively used for network routing, particularly in cloud infrastructure or network virtualization deployments, this vulnerability could be exploited to gain insights into the underlying network topology or system state. The attack surface is particularly concerning given that segment routing is increasingly deployed in enterprise and cloud environments where network security is paramount. The vulnerability could be leveraged as a stepping stone for more sophisticated attacks, potentially leading to privilege escalation or complete system compromise, especially when combined with other kernel vulnerabilities.
Mitigation strategies for CVE-2025-38310 should prioritize applying the official kernel patches that enforce exact length validation for nexthop addresses in the seg6 subsystem. Organizations should conduct immediate vulnerability assessments to identify systems running affected kernel versions and prioritize patch deployment across their infrastructure. Network administrators should monitor for any unusual network behavior or potential exploitation attempts, particularly in environments where segment routing is enabled. The fix implemented addresses the core validation issue by ensuring that provided length parameters exactly match the specified ones, preventing the kernel from accessing uninitialized memory regions. Security teams should also consider implementing network segmentation and monitoring to detect any anomalous packet routing patterns that might indicate exploitation attempts. Additionally, maintaining up-to-date kernel versions and following secure configuration practices for network routing protocols will help prevent similar vulnerabilities from emerging in the future, aligning with best practices recommended by the ATT&CK framework for kernel-level defense mechanisms.