{"answers":{"affected":"","exploited":"There is no known exploitation of CVE-2026-68398 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-68398 is a high-severity use after free vulnerability in Linux, published on 10 Aug 2026. 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-2026-68398 and fix it if it is affected.\n\nWhat it is: CVE-2026-68398 is a high-severity use after free vulnerability in Linux, published on 10 Aug 2026. 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-2026-68398 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-2026-68398/ (Markdown: https://insights.sbomify.com/CVE-2026-68398/index.md)","id":"CVE-2026-68398","markdown":"https://insights.sbomify.com/CVE-2026-68398/index.md","name":"CVE-2026-68398","record":{"aliases":["BELL-CVE-2026-68398","DEBIAN-CVE-2026-68398","GHSA-p572-44qq-qhm9","UBUNTU-CVE-2026-68398"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["code_execution","privilege_escalation"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel PPP","requires_auth":"low_privilege","summary":"An unprivileged user can trigger a use-after-free in the Linux kernel PPP L2TP receive path, potentially leading to code execution or privilege escalation.","user_interaction":"not_required","vuln_class":"use_after_free"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[],"cvss":{"score":7.8,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","version":"3.1"},"cwes":[{"id":"CWE-416","name":"Use After Free"}],"description":"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() -\u003e l2tp_recv_common() -\u003e pppol2tp_recv()\n   -\u003e ppp_input(\u0026po-\u003echan)\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-\u003eppp) 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) -\u003e pppol2tp_release() -\u003e pppox_unbind_sock()\n   -\u003e ppp_unregister_channel() -\u003e ppp_release_channel() -\u003e kfree(pch)\n\nFor a channel that is bound (PPPIOCGCHAN) but not attached to a ppp unit\n(no PPPIOCCONNECT, pch-\u003eppp == 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.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":"2026-08-12","github_poc":1,"max_poc_stars":10,"metasploit":0,"nuclei":0,"refs":[{"date":"2026-08-12T15:04:01Z","kind":"github_poc","ref":"https://github.com/aramosf/CVE-2026-68398","stars":10,"title":"CVE-2026-68398 Ubuntu PPPoL2TP use-after-free local privilege escalation"}],"tier":"poc_unverified"},"has_fix":true,"headline":"ppp: defer channel free to an RCU grace period to fix pppol2tp RX UAF","id":"CVE-2026-68398","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"use_after_free","year":"2026"},"n_packages":0,"n_references":7,"next":{"headline":"bpf: Fix UAF in sock clone early bailouts","id":"CVE-2026-68399"},"packages":[],"prev":{"headline":"net/iucv: take a reference on the socket found in afiucv_hs_rcv()","id":"CVE-2026-68397"},"products":["Linux"],"published":"2026-08-10","related":[],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"},{"class":"open","licence":"CC0","name":"PoC-in-GitHub"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-10-19","vendors":["Linux"]},"summary":"An unprivileged user can trigger a use-after-free in the Linux kernel PPP L2TP receive path, potentially leading to code execution or privilege escalation.","url":"https://insights.sbomify.com/CVE-2026-68398/"}