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CVE-2026-97965

vxlan: initialize _md in vxlan_xmit_one() PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: vxlan: initialize _md in vxlan_xmit_one() If a VXLAN device is configured with both VXLAN_F_COLLECT_METADATA and VXLAN_F_GBP, and a packet is transmitted through it using an external ip_tunnel_info that lacks the IP_TUNNEL_VXLAN_OPT_BIT flag, md is left pointing to the uninitialized _md stack variable: if (test_bit(IP_TUNNEL_VXLAN_OPT_BIT, info->key.tun_flags)) { if (info->options_len < sizeof(*md)) goto drop; md = ip_tunnel_info_opts(info); } Because IP_TUNNEL_VXLAN_OPT_BIT is not set, md is not updated and remains pointing to _md. Later, vxlan_build_skb() is called with md, which eventually calls vxlan_build_gbp_hdr(): if (vxflags & VXLAN_F_GBP) vxlan_build_gbp_hdr(vxh, md); Inside vxlan_build_gbp_hdr(), md->gbp is read: if (!md->gbp) return; gbp = (struct vxlanhdr_gbp *)vxh; ... if (md->gbp & VXLAN_GBP_DONT_LEARN) gbp->dont_learn = 1; If the stack contains garbage, this causes: 1) VXLAN_HF_GBP flag to be spuriously set in the VXLAN header. 2) gbp->dont_learn and gbp->policy_applied to be set from stack bits. 3) gbp->policy_id to receive 16 bits of uninitialized kernel stack data, leaking it onto the wire. Fix this by zero-initializing _md. If IP_TUNNEL_VXLAN_OPT_BIT is not present, md->gbp remains 0, and vxlan_build_gbp_hdr() returns early without modifying the VXLAN header.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected ee122c79d4227f6ec642157834b6a90fcffa4382 before fb78beb64e0e79557e4cd7cd17fea744bb6f01d9; affected ee122c79d4227f6ec642157834b6a90fcffa4382 before 0d13b5a413bffc8718b3821b78537ccc6596c233; affected ee122c79d4227f6ec642157834b6a90fcffa4382 before bfb74c48ac2d31476d5e09cf9658844508d2608a; affected ee122c79d4227f6ec642157834b6a90fcffa4382 before 081f22177d9d12b1e381b787f203cd5f47508187; affected ee122c79d4227f6ec642157834b6a90fcffa4382 before be83178bfc44588f6e3adb827ed874c683193466
Linux / Linuxaffected 4.3; unaffected 0 before 4.3; unaffected 6.6.160 through 6.6.*; unaffected 6.12.111 through 6.12.*; unaffected 6.18.53 through 6.18.*; unaffected 7.2.7 through 7.2.*; unaffected 7.3 through *

CWE

No CWE identifiers supplied.

References