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Mallory
Medium

Linux kernel BPF invalid GSO type emission via bpf_clone_redirect

IdentifiersCVE-2025-68725CWE-20

CVE-2025-68725 is a Linux kernel vulnerability in the BPF test infrastructure and networking path. A malformed skb could be emitted to the networking stack when a BPF program, triggered via the BPF test infrastructure, redirected a packet to the loopback device using bpf_clone_redirect(). The root cause was convert___skb_to_skb() populating gso_segs and gso_size without setting gso_type, resulting in inconsistent and invalid GSO metadata. This malformed state reached netif_skb_features() and gso_features_check(), where it triggered skb_warn_bad_offload(). The upstream fix rejects such malformed packets at bpf_clone_redirect() rather than allowing them to proceed further into the GSO handling path.

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ANALYST BRIEF

Impact, mitigation & remediation

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Impact

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Successful triggering of the flaw can cause skb_warn_bad_offload() warnings and disable GSO-related features for the malformed packet path, resulting in availability or performance degradation consistent with a denial-of-service style impact. The provided material does not indicate direct code execution or direct confidentiality/integrity compromise. Supporting advisory data rates the issue as local, low-complexity, low-privilege, with high availability impact.

Mitigation

If you can’t patch tonight, do this now.

Restrict or disable untrusted BPF program execution in affected environments, especially use of BPF test infrastructure paths capable of generating malformed packets. Avoid exposing workflows where BPF programs can invoke bpf_clone_redirect() on crafted packets toward loopback until patched. As an interim control, limit local low-privilege access to systems where untrusted users could exercise BPF functionality.

Remediation

Patch, then assume compromise.

Update to a Linux kernel release that includes the upstream fix for CVE-2025-68725, described as "bpf: Do not let BPF test infra emit invalid GSO types to stack," or apply the corresponding vendor backport. The fix rejects malformed packets at bpf_clone_redirect(). Where vendor guidance is relevant, deploy the fixed kernel packages provided by the distribution or platform maintainer.
PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

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VendorProductType
LinuxLinux Kerneloperating_system

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Threat actor evidence

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Associated malware

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Detection signatures

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Social activity3

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