In the Linux kernel, the following vulnerability has been resolved: net: dst_metadata: fix false-positive memcpy overflow in tun_dst_unclone kmalloc_flex() in metadata_dst_alloc() sets __counted_by for the structure to the options_len, which is then initialized to zero. Later, we're initializing the structure by copying the tunnel info together with the options, and this triggers a warning for a potential memcpy overflow, since the compiler estimates that the options can't fit into the structure, even though the memory for them is actually allocated. memcpy: detected buffer overflow: 104 byte write of buffer size 96 WARNING: CPU: X PID: Y at lib/string_helpers.c:1036 __fortify_report skb_tunnel_info_unclone+0x179/0x190 geneve_xmit+0x7fe/0xe00 The issue is triggered when built with clang and source fortification. Fix that by doing the copy in two stages: first - the main data with the options_len, then the options. This way the correct length should be known at the time of t
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This CVE exploits attack patterns that Casky's 0matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.
CVE-2026-80615 is a false-positive memory overflow detection in the Linux kernel's network subsystem, specifically in the dst_metadata module's tun_dst_unclone function. The vulnerability stems from a compiler instrumentation mismatch where kmalloc_flex() initializes a __counted_by annotation based on options_len set to zero, but legitimate subsequent operations copy tunnel metadata and options into the structure. This affects Linux kernel versions using the dst_metadata subsystem, impacting systems that handle tunneled network traffic, including containerized environments, VPNs, and cloud infrastructure. While not actively exploited, this impacts kernel stability and may cause denial of service through legitimate tunnel operations.
Casky.ai's security skills mapped to MITRE ATT&CK would correlate this vulnerability with T1499 (Service Exhaustion Denial of Service) patterns, as the false-positive overflow warning can cause kernel panic or memory allocation failures during normal tunnel operations. Practitioners using Casky would identify attack indicators through monitoring for unexpected kernel warnings, memory allocation failures on tunnel interface creation, or service disruptions in network function virtualization workloads. Extended reasoning across the 754 mapped skills enables detection of anomalous behavior in T1021 (Remote Service Session Initiation) scenarios where tunnel establishment attempts trigger memory safety warnings, helping security teams distinguish legitimate tunnel operations from potential exploitation attempts targeting kernel stability.
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