{"id":"CVE-2025-39673","summary":"ppp: fix race conditions in ppp_fill_forward_path","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nppp: fix race conditions in ppp_fill_forward_path\n\nppp_fill_forward_path() has two race conditions:\n\n1. The ppp-\u003echannels list can change between list_empty() and\n   list_first_entry(), as ppp_lock() is not held. If the only channel\n   is deleted in ppp_disconnect_channel(), list_first_entry() may\n   access an empty head or a freed entry, and trigger a panic.\n\n2. pch-\u003echan can be NULL. When ppp_unregister_channel() is called,\n   pch-\u003echan is set to NULL before pch is removed from ppp-\u003echannels.\n\nFix these by using a lockless RCU approach:\n- Use list_first_or_null_rcu() to safely test and access the first list\n  entry.\n- Convert list modifications on ppp-\u003echannels to their RCU variants and\n  add synchronize_net() after removal.\n- Check for a NULL pch-\u003echan before dereferencing it.","modified":"2026-05-28T03:55:41.752588661Z","published":"2025-09-05T17:20:38.769Z","related":["SUSE-SU-2025:21040-1","SUSE-SU-2025:21052-1","SUSE-SU-2025:21056-1","SUSE-SU-2025:21064-1","SUSE-SU-2025:21074-1","SUSE-SU-2025:21139-1","SUSE-SU-2025:21179-1","SUSE-SU-2025:4057-1","SUSE-SU-2025:4128-1","SUSE-SU-2025:4132-1","SUSE-SU-2025:4140-1","SUSE-SU-2025:4141-1","SUSE-SU-2025:4301-1","openSUSE-SU-2025:20081-1"],"database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39673.json"},"references":[{"type":"WEB","url":"https://cert-portal.siemens.com/productcert/html/ssa-032379.html"},{"type":"WEB","url":"https://git.kernel.org/stable/c/0417adf367a0af11adf7ace849af4638cfb573f7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/0f1630be6fcca3f0c63e4b242ad202e5cde28a40"},{"type":"WEB","url":"https://git.kernel.org/stable/c/94731cc551e29511d85aa8dec61a6c071b1f2430"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9a1969fbffc1f1900d92d7594b1b7d8d72ef3dc7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ca18d751bcc9faf5b7e82e9fae1223d103928181"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f97f6475fdcb3c28ff3c55cc4b7bde632119ec08"},{"type":"WEB","url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/39xxx/CVE-2025-39673.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-39673"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"f6efc675c9dd8d93f826b79ae7e33e03301db609"},{"fixed":"9a1969fbffc1f1900d92d7594b1b7d8d72ef3dc7"},{"fixed":"0f1630be6fcca3f0c63e4b242ad202e5cde28a40"},{"fixed":"ca18d751bcc9faf5b7e82e9fae1223d103928181"},{"fixed":"94731cc551e29511d85aa8dec61a6c071b1f2430"},{"fixed":"f97f6475fdcb3c28ff3c55cc4b7bde632119ec08"},{"fixed":"0417adf367a0af11adf7ace849af4638cfb573f7"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-39673.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.13.0"},{"fixed":"5.15.190"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.149"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.103"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.44"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.16.4"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2025-39673.json"}}],"schema_version":"1.7.5"}