{"id":"AZL-64022","summary":"CVE-2025-38037 affecting package kernel for versions less than 6.6.96.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nvxlan: Annotate FDB data races\n\nThe 'used' and 'updated' fields in the FDB entry structure can be\naccessed concurrently by multiple threads, leading to reports such as\n[1]. Can be reproduced using [2].\n\nSuppress these reports by annotating these accesses using\nREAD_ONCE() / WRITE_ONCE().\n\n[1]\nBUG: KCSAN: data-race in vxlan_xmit / vxlan_xmit\n\nwrite to 0xffff942604d263a8 of 8 bytes by task 286 on cpu 0:\n vxlan_xmit+0xb29/0x2380\n dev_hard_start_xmit+0x84/0x2f0\n __dev_queue_xmit+0x45a/0x1650\n packet_xmit+0x100/0x150\n packet_sendmsg+0x2114/0x2ac0\n __sys_sendto+0x318/0x330\n __x64_sys_sendto+0x76/0x90\n x64_sys_call+0x14e8/0x1c00\n do_syscall_64+0x9e/0x1a0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nread to 0xffff942604d263a8 of 8 bytes by task 287 on cpu 2:\n vxlan_xmit+0xadf/0x2380\n dev_hard_start_xmit+0x84/0x2f0\n __dev_queue_xmit+0x45a/0x1650\n packet_xmit+0x100/0x150\n packet_sendmsg+0x2114/0x2ac0\n __sys_sendto+0x318/0x330\n __x64_sys_sendto+0x76/0x90\n x64_sys_call+0x14e8/0x1c00\n do_syscall_64+0x9e/0x1a0\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nvalue changed: 0x00000000fffbac6e -\u003e 0x00000000fffbac6f\n\nReported by Kernel Concurrency Sanitizer on:\nCPU: 2 UID: 0 PID: 287 Comm: mausezahn Not tainted 6.13.0-rc7-01544-gb4b270f11a02 #5\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-3.fc41 04/01/2014\n\n[2]\n #!/bin/bash\n\n set +H\n echo whitelist \u003e /sys/kernel/debug/kcsan\n echo !vxlan_xmit \u003e /sys/kernel/debug/kcsan\n\n ip link add name vx0 up type vxlan id 10010 dstport 4789 local 192.0.2.1\n bridge fdb add 00:11:22:33:44:55 dev vx0 self static dst 198.51.100.1\n taskset -c 0 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q &\n taskset -c 2 mausezahn vx0 -a own -b 00:11:22:33:44:55 -c 0 -q &","modified":"2026-04-01T05:20:14.730833Z","published":"2025-06-18T10:15:36Z","upstream":["CVE-2025-38037"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-38037"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.96.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-64022.json"}}],"schema_version":"1.7.5"}