CVE-2025-37959

CVE Details

Release Date:	2025-05-20
Impact:	Moderate	What is this?

Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Scrub packet on bpf_redirect_peer When bpf_redirect_peer is used to redirect packets to a device in another network namespace, the skb isn't scrubbed. That can lead skb information from one namespace to be "misused" in another namespace. As one example, this is causing Cilium to drop traffic when using bpf_redirect_peer to redirect packets that just went through IPsec decryption to a container namespace. The following pwru trace shows (1) the packet path from the host's XFRM layer to the container's XFRM layer where it's dropped and (2) the number of active skb extensions at each function. NETNS MARK IFACE TUPLE FUNC 4026533547 d00 eth0 10.244.3.124:35473->10.244.2.158:53 xfrm_rcv_cb .active_extensions = (__u8)2, 4026533547 d00 eth0 10.244.3.124:35473->10.244.2.158:53 xfrm4_rcv_cb .active_extensions = (__u8)2, 4026533547 d00 eth0 10.244.3.124:35473->10.244.2.158:53 gro_cells_receive .active_extensions = (__u8)2, [...] 4026533547 0 eth0 10.244.3.124:35473->10.244.2.158:53 skb_do_redirect .active_extensions = (__u8)2, 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 ip_rcv .active_extensions = (__u8)2, 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 ip_rcv_core .active_extensions = (__u8)2, [...] 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 udp_queue_rcv_one_skb .active_extensions = (__u8)2, 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 __xfrm_policy_check .active_extensions = (__u8)2, 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 __xfrm_decode_session .active_extensions = (__u8)2, 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 security_xfrm_decode_session .active_extensions = (__u8)2, 4026534999 0 eth0 10.244.3.124:35473->10.244.2.158:53 kfree_skb_reason(SKB_DROP_REASON_XFRM_POLICY) .active_extensions = (__u8)2, In this case, there are no XFRM policies in the container's network namespace so the drop is unexpected. When we decrypt the IPsec packet, the XFRM state used for decryption is set in the skb extensions. This information is preserved across the netns switch. When we reach the XFRM policy check in the container's netns, __xfrm_policy_check drops the packet with LINUX_MIB_XFRMINNOPOLS because a (container-side) XFRM policy can't be found that matches the (host-side) XFRM state used for decryption. This patch fixes this by scrubbing the packet when using bpf_redirect_peer, as is done on typical netns switches via veth devices except skb->mark and skb->tstamp are not zeroed.

See more information about CVE-2025-37959 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	4.7
Vector String:	CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
Version:	3.1
Attack Vector:	Local
Attack Complexity:	High
Privileges Required:	Low
User Interaction:	None
Scope:	Unchanged
Confidentiality Impact:	None
Integrity Impact:	None
Availability Impact:	High

Errata information

Platform	Errata	Release Date
Oracle Linux version 10 (kernel-uek)	ELSA-2025-20480	2025-07-17
Oracle Linux version 9 (kernel-uek)	ELSA-2025-20480	2025-07-17