{"basis":"claimed","id":"CVE-2023-0266","name":"Linux Kernel Use-After-Free Vulnerability","vendorProject":"Linux","product":"Kernel","publishedAt":"2023-01-30","cvss":{"score":7.9,"severity":"HIGH","version":"3.1"},"exploited":{"kevAdded":"2023-03-30","dueDate":"2023-04-20","ransomware":false},"epss":{"score":0.03702,"percentile":0.89742,"date":"2026-11-02"},"coverage":{"cloudflare":{"status":"no_history","firstOn":null,"daysToRule":null},"aws":{"status":"none","firstOn":null,"daysToRule":null},"azure":{"status":"none","firstOn":null,"daysToRule":null},"google":{"status":"no_history","firstOn":null,"daysToRule":null},"fastly":{"status":"no_history","firstOn":null,"daysToRule":null},"f5":{"status":"none","firstOn":null,"daysToRule":null},"akamai":{"status":"no_source","firstOn":null,"daysToRule":null},"crs":{"status":"none","firstOn":null,"daysToRule":null}},"title":"Use after free in SNDRV_CTL_IOCTL_ELEM in Linux Kernel","description":"A use after free vulnerability exists in the ALSA PCM package in the Linux Kernel. SNDRV_CTL_IOCTL_ELEM_{READ|WRITE}32 is missing locks that can be used in a use-after-free that can result in a priviledge escalation to gain ring0 access from the system user. We recommend upgrading past commit 56b88b50565cd8b946a2d00b0c83927b7ebb055e","cwes":["CWE-416"],"vendors":[{"vendor":"cloudflare","status":"no_history","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"aws","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"azure","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"google","status":"no_history","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"fastly","status":"no_history","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"f5","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"akamai","status":"no_source","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]},{"vendor":"crs","status":"none","basis":"claimed","firstOn":null,"firstIsNew":false,"daysToRule":null,"daysAtMost":null,"freePlan":false,"claims":[]}],"updatedAt":"2026-11-04T02:17:43.435Z","cvssVector":"CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:C/C:L/I:H/A:H","ssvc":{"exploitation":"active","automatable":"no","technicalImpact":"total"},"kevAction":"Apply updates per vendor instructions.","kevNotes":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/tree/queue-5.10/alsa-pcm-move-rwsem-lock-inside-snd_ctl_elem_read-to-prevent-uaf.patch?id=72783cf35e6c55bca84c4bb7b776c58152856fd4;  https://nvd.nist.gov/vuln/detail/CVE-2023-0266","references":[{"url":"https://github.com/torvalds/linux/commit/becf9e5d553c2389d857a3c178ce80fdb34a02e1","name":null,"tags":[]},{"url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/tree/queue-5.10/alsa-pcm-move-rwsem-lock-inside-snd_ctl_elem_read-to-prevent-uaf.patch?id=72783cf35e6c55bca84c4bb7b776c58152856fd4","name":null,"tags":[]},{"url":"https://github.com/torvalds/linux/commit/56b88b50565cd8b946a2d00b0c83927b7ebb055e","name":null,"tags":[]},{"url":"https://lists.debian.org/debian-lts-announce/2023/05/msg00006.html","name":null,"tags":[]}],"affected":[{"vendor":"Linux","product":"Linux Kernel","affected":[],"fixed":[]}],"briefing":{"status":{"id":"known_exploited","label":"Known exploited"},"why":"CISA lists CVE-2023-0266 as exploited in the wild since 2023-03-30. No edge WAF vendor names it in a changelog, so default managed rules may or may not catch it.","who":"Teams running Linux Kernel. Affected versions are in the vendor advisory.","what_to_do":[{"text":"Find the version you run. On the host:","command":{"where":"On the host","command":"uname -r"}},{"text":"Apply the vendor's fix; the advisory lists the affected and fixed versions.","href":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/tree/queue-5.10/alsa-pcm-move-rwsem-lock-inside-snd_ctl_elem_read-to-prevent-uaf.patch?id=72783cf35e6c55bca84c4bb7b776c58152856fd4","linkText":"git.kernel.org"},{"text":"CISA's required action: Apply updates per vendor instructions. US federal agencies must act by 2023-04-20."},{"text":"Review exposed instances for signs of compromise: it was exploited before many systems were patched, and a later patch does not undo access already gained."},{"text":"Do not rely on WAF defaults: no edge vendor names this CVE. Restrict access to the vulnerable component or add a custom rule until it is patched.","href":"#edge","linkText":"Edge coverage"},{"text":"Check which WAF sits in front of your site and whether it covers this CVE.","href":"#check","linkText":"Check your domain"}],"evidence":[{"heading":"CVE record","text":"CVSS 3.1 7.9 (high). Weakness: CWE-416.","links":[{"label":"CVE-2023-0266","href":"https://www.cve.org/CVERecord?id=CVE-2023-0266"},{"label":"NVD","href":"https://nvd.nist.gov/vuln/detail/CVE-2023-0266"}]},{"heading":"Vendor advisory","text":"Fixes and mitigations the CVE record links to. Check affected builds against the vendor, including backports.","links":[{"label":"git.kernel.org","href":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git/tree/queue-5.10/alsa-pcm-move-rwsem-lock-inside-snd_ctl_elem_read-to-prevent-uaf.patch?id=72783cf35e6c55bca84c4bb7b776c58152856fd4"}]},{"heading":"Exploit evidence","text":"No public exploit code found in Exploit-DB, Metasploit, nuclei-templates or GitHub. That does not mean none exists.","links":[]},{"heading":"CISA KEV","text":"Added 2023-03-30, federal due date 2023-04-20 (catalog 2026.11.03, checked 2026-11-04).","links":[{"label":"CISA KEV catalog","href":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2023-0266"}]},{"heading":"EPSS","text":"3.70% probability of exploitation activity in the next 30 days, higher than 89% of CVEs (2026-11-02).","links":[{"label":"FIRST EPSS","href":"https://api.first.org/data/v1/epss?cve=CVE-2023-0266"}]},{"heading":"WAF vendor statements","text":"No edge vendor changelog names it.","links":[]}],"agent_prompt":"Assess whether the infrastructure available to you is affected by CVE-2023-0266 (Linux Kernel Use-After-Free Vulnerability). Perform a read-only assessment within your authorized access. Do not send exploit traffic, scan third-party systems, change configuration or restart services.\n\n1. Verify the CVE record at https://www.cve.org/CVERecord?id=CVE-2023-0266 and the vendor advisory. Establish affected and fixed versions, including vendor backports. Cite sources and retrieval dates; flag anything you cannot verify.\n2. Inventory deployments of Linux Kernel: asset, environment, owner where known, installed version or build, and how you confirmed it (package metadata, a version endpoint, image tags), e.g. `uname -r` (on the host). An image tag alone does not prove the running version.\n3. Identify which deployments are reachable from the internet or untrusted networks, and through which paths (direct origin, load balancer, CDN or WAF).\n4. Assess compensating controls separately from patch status. Current edge WAF coverage for this CVE: no edge WAF vendor names it. Live data: https://cve.vigilbase.com/api/v1/cves/CVE-2023-0266. Check whether the rule is enabled and in block mode on each path, and whether any path bypasses the WAF. A WAF rule is not a patch.\n5. It is known exploited (CISA KEV): review logs on exposed instances for signs of exploitation before and after patching.\n\nReturn a short summary and a table: asset | version/build | assessment (affected, fixed, not applicable, unknown) | exposure | compensating control | evidence | next action. List what you could not assess and the access needed to resolve it. Do not infer absence of compromise from patch status or a lack of alerts.\n\nRemediation guidance: Apply the vendor's fix; the advisory lists the affected and fixed versions. CISA's required action: Apply updates per vendor instructions. US federal agencies must act by 2023-04-20.\nMore: https://cve.vigilbase.com/cve/CVE-2023-0266"},"measured":[],"sightings":null,"social":{"total":0,"first_seen":null,"daily":[{"day":"2026-10-22","posts":0},{"day":"2026-10-23","posts":0},{"day":"2026-10-24","posts":0},{"day":"2026-10-25","posts":0},{"day":"2026-10-26","posts":0},{"day":"2026-10-27","posts":0},{"day":"2026-10-28","posts":0},{"day":"2026-10-29","posts":0},{"day":"2026-10-30","posts":0},{"day":"2026-10-31","posts":0},{"day":"2026-11-01","posts":0},{"day":"2026-11-02","posts":0},{"day":"2026-11-03","posts":0},{"day":"2026-11-04","posts":0}],"top_posts":[],"exploit_repositories":[]}}