{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2026-23209 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2026-23209 is a high-severity use after free vulnerability in Linux kernel, published on 14 Feb 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-2026-23209 and fix it if it is affected.\n\nWhat it is: CVE-2026-23209 is a high-severity use after free vulnerability in Linux kernel, published on 14 Feb 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-2026-23209 in the wild and no public exploit code.\n\nAffected product: Linux kernel. 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-2026-23209/ (Markdown: https://insights.sbomify.com/CVE-2026-23209/index.md)","id":"CVE-2026-23209","markdown":"https://insights.sbomify.com/CVE-2026-23209/index.md","name":"CVE-2026-23209","record":{"aliases":["AZL-77739","BELL-CVE-2026-23209","CLSA-2026-1784274653","DEBIAN-CVE-2026-23209","GHSA-89j4-f3cq-gm32","ROOT-OS-DEBIAN-11-CVE-2026-23209","ROOT-OS-DEBIAN-12-CVE-2026-23209","ROOT-OS-DEBIAN-13-CVE-2026-23209","ROOT-OS-UBUNTU-2204-CVE-2026-23209","ROOT-OS-UBUNTU-2404-CVE-2026-23209","SUSE-SU-2026:1231-1","UBUNTU-CVE-2026-23209"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service","code_execution"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"A use-after-free in the Linux kernel macvlan driver allows local attackers to crash the system or potentially execute code via crafted network link configurations.","user_interaction":"not_required","vuln_class":"use_after_free"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"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\nmacvlan: fix error recovery in macvlan_common_newlink()\n\nvalis provided a nice repro to crash the kernel:\n\nip link add p1 type veth peer p2\nip link set address 00:00:00:00:00:20 dev p1\nip link set up dev p1\nip link set up dev p2\n\nip link add mv0 link p2 type macvlan mode source\nip link add invalid% link p2 type macvlan mode source macaddr add 00:00:00:00:00:20\n\nping -c1 -I p1 1.2.3.4\n\nHe also gave a very detailed analysis:\n\n\u003cquote valis\u003e\n\nThe issue is triggered when a new macvlan link is created  with\nMACVLAN_MODE_SOURCE mode and MACVLAN_MACADDR_ADD (or\nMACVLAN_MACADDR_SET) parameter, lower device already has a macvlan\nport and register_netdevice() called from macvlan_common_newlink()\nfails (e.g. because of the invalid link name).\n\nIn this case macvlan_hash_add_source is called from\nmacvlan_change_sources() / macvlan_common_newlink():\n\nThis adds a reference to vlan to the port's vlan_source_hash using\nmacvlan_source_entry.\n\nvlan is a pointer to the priv data of the link that is being created.\n\nWhen register_netdevice() fails, the error is returned from\nmacvlan_newlink() to rtnl_newlink_create():\n\n        if (ops-\u003enewlink)\n                err = ops-\u003enewlink(dev, \u0026params, extack);\n        else\n                err = register_netdevice(dev);\n        if (err \u003c 0) {\n                free_netdev(dev);\n                goto out;\n        }\n\nand free_netdev() is called, causing a kvfree() on the struct\nnet_device that is still referenced in the source entry attached to\nthe lower device's macvlan port.\n\nNow all packets sent on the macvlan port with a matching source mac\naddress will trigger a use-after-free in macvlan_forward_source().\n\n\u003c/quote valis\u003e\n\nWith all that, my fix is to make sure we call macvlan_flush_sources()\nregardless of @create value whenever \"goto destroy_macvlan_port;\"\npath is taken.\n\nMany thanks to valis for following up on this issue.","ecosystems":["SUSE:Linux Enterprise Live Patching 15 SP4"],"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":"macvlan: fix error recovery in macvlan_common_newlink()","id":"CVE-2026-23209","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"use_after_free","year":"2026"},"n_packages":1,"n_references":7,"next":{"headline":"ice: Fix PTP NULL pointer dereference during VSI rebuild","id":"CVE-2026-23210"},"packages":[{"ecosystem":"SUSE:Linux Enterprise Live Patching 15 SP4","fixed":["2-150400.2.1"],"introduced":["0"],"last_affected":[],"package":"kernel-livepatch-SLE15-SP4_Update_48","purl":"pkg:rpm/suse/kernel-livepatch-SLE15-SP4_Update_48\u0026distro=SUSE%20Linux%20Enterprise%20Live%20Patching%2015%20SP4","source":"SUSE-SU-2026:1231-1"}],"prev":{"headline":"ALSA: usb-audio: Prevent excessive number of frames","id":"CVE-2026-23208"},"products":["Linux"],"published":"2026-02-14","related":[{"cvss_score":8.8,"headline":"Linux Kernel Out-of-Bounds Write","id":"CVE-2026-53266","kev_date_added":"2026-09-18","published":"2026-06-25"},{"cvss_score":8.8,"headline":"Linux Kernel Improper Input Validation","id":"CVE-2013-6282","kev_date_added":"2022-09-15","published":"2013-11-19"},{"cvss_score":8.4,"headline":"Linux Kernel Heap-Based Buffer Overflow","id":"CVE-2022-0185","kev_date_added":"2024-08-21","published":"2022-02-11"},{"cvss_score":8.4,"headline":"Linux Kernel Privilege Escalation","id":"CVE-2013-2094","kev_date_added":"2022-09-15","published":"2013-05-14"},{"cvss_score":7.8,"headline":"Linux Kernel Unspecified","id":"CVE-2026-53362","kev_date_added":"2026-08-27","published":"2026-07-04"},{"cvss_score":7.8,"headline":"Linux Kernel Missing Initialization of a Variable","id":"CVE-2026-46300","kev_date_added":"2026-10-28","published":"2026-05-23"},{"cvss_score":7.8,"headline":"Linux Kernel Race Condition","id":"CVE-2025-39964","kev_date_added":"2026-09-18","published":"2025-10-13"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"SUSE","prefix":"SUSE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"total"},"state":"PUBLISHED","updated":"2026-10-19","vendors":["Linux"]},"summary":"A use-after-free in the Linux kernel macvlan driver allows local attackers to crash the system or potentially execute code via crafted network link configurations.","url":"https://insights.sbomify.com/CVE-2026-23209/"}