{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2023-53809 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2023-53809 is a vulnerability in Linux, published on 9 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2023-53809 and fix it if it is affected.\n\nWhat it is: CVE-2023-53809 is a vulnerability in Linux, published on 9 Dec 2025. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2023-53809 in the wild and no public exploit code.\n\nAffected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2023-53809/ (Markdown: https://insights.sbomify.com/CVE-2023-53809/index.md)","id":"CVE-2023-53809","markdown":"https://insights.sbomify.com/CVE-2023-53809/index.md","name":"CVE-2023-53809","record":{"aliases":["BELL-CVE-2023-53809","DEBIAN-CVE-2023-53809","GHSA-f2xq-v5p2-cqjf","UBUNTU-CVE-2023-53809"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"A local attacker can cause a kernel deadlock in the L2TP tunnel registration by passing a specific socket file descriptor, leading to denial of service.","user_interaction":"not_required","vuln_class":"race_condition"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[],"cvss":{"score":null,"severity":null,"source":null,"vector":null,"version":null},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nl2tp: Avoid possible recursive deadlock in l2tp_tunnel_register()\n\nWhen a file descriptor of pppol2tp socket is passed as file descriptor\nof UDP socket, a recursive deadlock occurs in l2tp_tunnel_register().\nThis situation is reproduced by the following program:\n\nint main(void)\n{\n\tint sock;\n\tstruct sockaddr_pppol2tp addr;\n\n\tsock = socket(AF_PPPOX, SOCK_DGRAM, PX_PROTO_OL2TP);\n\tif (sock \u003c 0) {\n\t\tperror(\"socket\");\n\t\treturn 1;\n\t}\n\n\taddr.sa_family = AF_PPPOX;\n\taddr.sa_protocol = PX_PROTO_OL2TP;\n\taddr.pppol2tp.pid = 0;\n\taddr.pppol2tp.fd = sock;\n\taddr.pppol2tp.addr.sin_family = PF_INET;\n\taddr.pppol2tp.addr.sin_port = htons(0);\n\taddr.pppol2tp.addr.sin_addr.s_addr = inet_addr(\"192.168.0.1\");\n\taddr.pppol2tp.s_tunnel = 1;\n\taddr.pppol2tp.s_session = 0;\n\taddr.pppol2tp.d_tunnel = 0;\n\taddr.pppol2tp.d_session = 0;\n\n\tif (connect(sock, (const struct sockaddr *)\u0026addr, sizeof(addr)) \u003c 0) {\n\t\tperror(\"connect\");\n\t\treturn 1;\n\t}\n\n\treturn 0;\n}\n\nThis program causes the following lockdep warning:\n\n ============================================\n WARNING: possible recursive locking detected\n 6.2.0-rc5-00205-gc96618275234 #56 Not tainted\n --------------------------------------------\n repro/8607 is trying to acquire lock:\n ffff8880213c8130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: l2tp_tunnel_register+0x2b7/0x11c0\n\n but task is already holding lock:\n ffff8880213c8130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppol2tp_connect+0xa82/0x1a30\n\n other info that might help us debug this:\n  Possible unsafe locking scenario:\n\n        CPU0\n        ----\n   lock(sk_lock-AF_PPPOX);\n   lock(sk_lock-AF_PPPOX);\n\n  *** DEADLOCK ***\n\n  May be due to missing lock nesting notation\n\n 1 lock held by repro/8607:\n  #0: ffff8880213c8130 (sk_lock-AF_PPPOX){+.+.}-{0:0}, at: pppol2tp_connect+0xa82/0x1a30\n\n stack backtrace:\n CPU: 0 PID: 8607 Comm: repro Not tainted 6.2.0-rc5-00205-gc96618275234 #56\n Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.1-2.fc37 04/01/2014\n Call Trace:\n  \u003cTASK\u003e\n  dump_stack_lvl+0x100/0x178\n  __lock_acquire.cold+0x119/0x3b9\n  ? lockdep_hardirqs_on_prepare+0x410/0x410\n  lock_acquire+0x1e0/0x610\n  ? l2tp_tunnel_register+0x2b7/0x11c0\n  ? lock_downgrade+0x710/0x710\n  ? __fget_files+0x283/0x3e0\n  lock_sock_nested+0x3a/0xf0\n  ? l2tp_tunnel_register+0x2b7/0x11c0\n  l2tp_tunnel_register+0x2b7/0x11c0\n  ? sprintf+0xc4/0x100\n  ? l2tp_tunnel_del_work+0x6b0/0x6b0\n  ? debug_object_deactivate+0x320/0x320\n  ? lockdep_init_map_type+0x16d/0x7a0\n  ? lockdep_init_map_type+0x16d/0x7a0\n  ? l2tp_tunnel_create+0x2bf/0x4b0\n  ? l2tp_tunnel_create+0x3c6/0x4b0\n  pppol2tp_connect+0x14e1/0x1a30\n  ? pppol2tp_put_sk+0xd0/0xd0\n  ? aa_sk_perm+0x2b7/0xa80\n  ? aa_af_perm+0x260/0x260\n  ? bpf_lsm_socket_connect+0x9/0x10\n  ? pppol2tp_put_sk+0xd0/0xd0\n  __sys_connect_file+0x14f/0x190\n  __sys_connect+0x133/0x160\n  ? __sys_connect_file+0x190/0x190\n  ? lockdep_hardirqs_on+0x7d/0x100\n  ? ktime_get_coarse_real_ts64+0x1b7/0x200\n  ? ktime_get_coarse_real_ts64+0x147/0x200\n  ? __audit_syscall_entry+0x396/0x500\n  __x64_sys_connect+0x72/0xb0\n  do_syscall_64+0x38/0xb0\n  entry_SYSCALL_64_after_hwframe+0x63/0xcd\n\nThis patch fixes the issue by getting/creating the tunnel before\nlocking the pppol2tp socket.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"l2tp: Avoid possible recursive deadlock in l2tp_tunnel_register()","id":"CVE-2023-53809","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"race_condition","year":"2023"},"n_packages":0,"n_references":5,"next":{"headline":"blk-mq: release crypto keyslot before reporting I/O complete","id":"CVE-2023-53810"},"packages":[],"prev":{"headline":"wifi: mwifiex: fix memory leak in mwifiex_histogram_read()","id":"CVE-2023-53808"},"products":["Linux"],"published":"2025-12-09","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-05-23","vendors":["Linux"]},"summary":"A local attacker can cause a kernel deadlock in the L2TP tunnel registration by passing a specific socket file descriptor, leading to denial of service.","url":"https://insights.sbomify.com/CVE-2023-53809/"}