In the Linux kernel, the following vulnerability has been resolved: ip: orphan prefetched skbs before multicast forwarding IPv4 and IPv6 input… (CVE-2026-89564)
A vulnerability in the Linux kernel involving improper handling of socket references during multicast forwarding for IPv4 and IPv6 has been resolved. The issue occurs because prefetched sockets may be destroyed before the associated socket reference is released, leading to dereferencing of a stale socket pointer when the skb (socket buffer) is freed. The fix involves orphaning the skb before non-local multicast forwarding to avoid use-after-free conditions. This vulnerability affects the kernel's network stack handling of multicast packets and socket associations.
AI Analysis
Technical Summary
The Linux kernel vulnerability (CVE-2026-89564) involves the preservation of skb->sk socket associations installed by bpf_sk_assign() during IPv4 and IPv6 input processing. Both BPF and UDP early demux paths prefetch sockets without guaranteed references. When multicast packets are not locally deliverable, the original skb is forwarded or queued without orphaning, leading to a use-after-free scenario when the prefetched socket is destroyed and the skb is freed, causing sock_pfree() to dereference a stale skb->sk pointer. The resolution is to orphan the skb before each non-local multicast forwarding path, ensuring socket-free clones are used for multicast forwarding.
Potential Impact
This vulnerability could lead to kernel memory corruption or crashes due to dereferencing stale socket pointers during multicast packet forwarding. It affects the stability and security of the Linux kernel network stack, potentially allowing attackers to cause denial of service or other unintended kernel behavior. No known exploits in the wild have been reported.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to orphan the skb before non-local multicast forwarding, preventing use-after-free of socket references. Users should apply the official kernel updates that include this fix. Since this is a kernel vulnerability, upgrading to the patched kernel version is the recommended remediation. No additional mitigation steps are indicated.
In the Linux kernel, the following vulnerability has been resolved: ip: orphan prefetched skbs before multicast forwarding IPv4 and IPv6 input… (CVE-2026-89564)
Description
A vulnerability in the Linux kernel involving improper handling of socket references during multicast forwarding for IPv4 and IPv6 has been resolved. The issue occurs because prefetched sockets may be destroyed before the associated socket reference is released, leading to dereferencing of a stale socket pointer when the skb (socket buffer) is freed. The fix involves orphaning the skb before non-local multicast forwarding to avoid use-after-free conditions. This vulnerability affects the kernel's network stack handling of multicast packets and socket associations.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel vulnerability (CVE-2026-89564) involves the preservation of skb->sk socket associations installed by bpf_sk_assign() during IPv4 and IPv6 input processing. Both BPF and UDP early demux paths prefetch sockets without guaranteed references. When multicast packets are not locally deliverable, the original skb is forwarded or queued without orphaning, leading to a use-after-free scenario when the prefetched socket is destroyed and the skb is freed, causing sock_pfree() to dereference a stale skb->sk pointer. The resolution is to orphan the skb before each non-local multicast forwarding path, ensuring socket-free clones are used for multicast forwarding.
Potential Impact
This vulnerability could lead to kernel memory corruption or crashes due to dereferencing stale socket pointers during multicast packet forwarding. It affects the stability and security of the Linux kernel network stack, potentially allowing attackers to cause denial of service or other unintended kernel behavior. No known exploits in the wild have been reported.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to orphan the skb before non-local multicast forwarding, preventing use-after-free of socket references. Users should apply the official kernel updates that include this fix. Since this is a kernel vulnerability, upgrading to the patched kernel version is the recommended remediation. No additional mitigation steps are indicated.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-94m9-vxgj-4qq7
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-89564"]
Threat ID: 6aa4a00f55bf5e2cf5a866a8
Added to database: 09/12/2026, 00:42:55 UTC
Last enriched: 09/12/2026, 01:06:35 UTC
Last updated: 09/12/2026, 01:06:35 UTC
Views: 2
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