{"id":"AZL-56396","summary":"CVE-2025-21670 affecting package kernel for versions less than 6.6.76.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nvsock/bpf: return early if transport is not assigned\n\nSome of the core functions can only be called if the transport\nhas been assigned.\n\nAs Michal reported, a socket might have the transport at NULL,\nfor example after a failed connect(), causing the following trace:\n\n    BUG: kernel NULL pointer dereference, address: 00000000000000a0\n    #PF: supervisor read access in kernel mode\n    #PF: error_code(0x0000) - not-present page\n    PGD 12faf8067 P4D 12faf8067 PUD 113670067 PMD 0\n    Oops: Oops: 0000 [#1] PREEMPT SMP NOPTI\n    CPU: 15 UID: 0 PID: 1198 Comm: a.out Not tainted 6.13.0-rc2+\n    RIP: 0010:vsock_connectible_has_data+0x1f/0x40\n    Call Trace:\n     vsock_bpf_recvmsg+0xca/0x5e0\n     sock_recvmsg+0xb9/0xc0\n     __sys_recvfrom+0xb3/0x130\n     __x64_sys_recvfrom+0x20/0x30\n     do_syscall_64+0x93/0x180\n     entry_SYSCALL_64_after_hwframe+0x76/0x7e\n\nSo we need to check the `vsk-\u003etransport` in vsock_bpf_recvmsg(),\nespecially for connected sockets (stream/seqpacket) as we already\ndo in __vsock_connectible_recvmsg().","modified":"2026-04-21T04:36:08.281122Z","published":"2025-01-31T12:15:28Z","upstream":["CVE-2025-21670"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-21670"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.6.76.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-56396.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}