{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2026-68398", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-68398", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-08-10T12:04:17.771Z", "updatedAt": "2026-10-19T21:09:08.443Z", "importedAt": "2026-10-24T01:58:25.636Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "ppp: defer channel free to an RCU grace period to fix pppol2tp RX UAF", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nppp: defer channel free to an RCU grace period to fix pppol2tp RX UAF\n\npppol2tp_recv() runs in the L2TP UDP-encap softirq RX path:\n\n l2tp_udp_encap_recv() -> l2tp_recv_common() -> pppol2tp_recv()\n -> ppp_input(&po->chan)\n\nIt runs under rcu_read_lock() holding only an l2tp_session reference and\ntakes NO reference on the internal PPP channel (struct channel,\nchan->ppp) that ppp_input() dereferences.\n\nThe pppox socket is SOCK_RCU_FREE, so 'po' and the embedded ppp_channel\nare RCU-safe. But the internal struct channel is a separate allocation\nthat ppp_release_channel() frees with a plain kfree():\n\n close(data socket) -> pppol2tp_release() -> pppox_unbind_sock()\n -> ppp_unregister_channel() -> ppp_release_channel() -> kfree(pch)\n\nFor a channel that is bound (PPPIOCGCHAN) but not attached to a ppp unit\n(no PPPIOCCONNECT, pch->ppp == NULL) and not bridged, teardown skips\nboth ppp_disconnect_channel()'s synchronize_net() and\nppp_unbridge_channels()'s synchronize_rcu(), so the kfree() has no grace\nperiod. rcu_read_lock() in pppol2tp_recv() does not protect against a\nplain kfree(), so an in-flight ppp_input() on one CPU can dereference\nthe channel just freed by close() on another CPU.\n\nThe bug is reachable by an unprivileged user.\n\nDefer the channel free to an RCU callback via call_rcu() so the grace\nperiod fences any in-flight ppp_input(). The disconnect and unbridge\nteardown paths already fence with synchronize_net()/synchronize_rcu();\ncall_rcu() does the same here without stalling the close() path.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741", "status": "affected", "versionType": "git", "lessThan": "4e47f1ac188ece11d6fdabe44166a2776cc5bd4e" }, { "version": "ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741", "status": "affected", "versionType": "git", "lessThan": "110b765744b147c63882f5e9cb12931c5dc8d85f" }, { "version": "ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741", "status": "affected", "versionType": "git", "lessThan": "4bb84e964ff0fe0a171c965362de72f9820dbce9" }, { "version": "ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741", "status": "affected", "versionType": "git", "lessThan": "3ab32218d7182705dae5c86f13925f458072da2c" }, { "version": "ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741", "status": "affected", "versionType": "git", "lessThan": "c9574b8a8edeb4edd3ac6472c27ef7184bdb2baa" }, { "version": "ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741", "status": "affected", "versionType": "git", "lessThan": "06213c85d8c0994f786c093b8b2a517987943ca6" }, { "version": "ee40fb2e1eb5bc0ddd3f2f83c6e39a454ef5a741", "status": "affected", "versionType": "git", "lessThan": "ec4215683e47424c9c4762fd3c60f552a3119142" }, { "version": "d36e5ba7bbed5d7bd26e8609ffed503c2def401b", "status": "affected", "versionType": "git" }, { "version": "9bcc0508576b2d50efd958f2ea1c5906749c2c89", "status": "affected", "versionType": "git" }, { "version": "c2984681fe15cfb803a9132aaaf1140ab20a72c1", "status": "affected", "versionType": "git" }, { "version": "5803ecd7f6ac6f747582e775caa62ac9d0489261", "status": "affected", "versionType": "git" }, { "version": "26f8819ddd10141ebe7bbce700fbab36bfa5f478", "status": "affected", "versionType": "git" }, { "version": "3.2.99", "status": "affected", "versionType": "semver", "lessThan": "3.3" }, { "version": "3.16.54", "status": "affected", "versionType": "semver", "lessThan": "3.17" }, { "version": "4.4.225", "status": "affected", "versionType": "semver", "lessThan": "4.5" }, { "version": "4.9.225", "status": "affected", "versionType": "semver", "lessThan": "4.10" }, { "version": "4.14.182", "status": "affected", "versionType": "semver", "lessThan": "4.15" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "4.15", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "4.15" }, { "version": "5.15.216", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.183", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.148", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.101", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.42", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.1.6", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.1.*" }, { "version": "7.2", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }