{"api_version":"1","generated_at":"2026-04-23T03:25:26+00:00","cve":"CVE-2019-18423","urls":{"html":"https://cve.report/CVE-2019-18423","api":"https://cve.report/api/cve/CVE-2019-18423.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2019-18423","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2019-18423"},"summary":{"title":"CVE-2019-18423","description":"An issue was discovered in Xen through 4.12.x allowing ARM guest OS users to cause a denial of service via a XENMEM_add_to_physmap hypercall. p2m->max_mapped_gfn is used by the functions p2m_resolve_translation_fault() and p2m_get_entry() to sanity check guest physical frame. The rest of the code in the two functions will assume that there is a valid root table and check that with BUG_ON(). The function p2m_get_root_pointer() will ignore the unused top bits of a guest physical frame. This means that the function p2m_set_entry() will alias the frame. However, p2m->max_mapped_gfn will be updated using the original frame. It would be possible to set p2m->max_mapped_gfn high enough to cover a frame that would lead p2m_get_root_pointer() to return NULL in p2m_get_entry() and p2m_resolve_translation_fault(). Additionally, the sanity check on p2m->max_mapped_gfn is off-by-one allowing \"highest mapped + 1\" to be considered valid. However, p2m_get_root_pointer() will return NULL. The problem could be triggered with a specially crafted hypercall XENMEM_add_to_physmap{, _batch} followed by an access to an address (via hypercall or direct access) that passes the sanity check but cause p2m_get_root_pointer() to return NULL. A malicious guest administrator may cause a hypervisor crash, resulting in a Denial of Service (DoS). Xen version 4.8 and newer are vulnerable. Only Arm systems are vulnerable. x86 systems are not affected.","state":"PUBLIC","assigner":"cve@mitre.org","published_at":"2019-10-31 14:15:00","updated_at":"2023-11-07 03:06:00"},"problem_types":["CWE-193"],"metrics":[],"references":[{"url":"https://www.debian.org/security/2020/dsa-4602","name":"DSA-4602","refsource":"DEBIAN","tags":[],"title":"Debian -- Security Information -- DSA-4602-1 xen","mime":"text/html","httpstatus":"200","archivestatus":"200"},{"url":"https://security.gentoo.org/glsa/202003-56","name":"GLSA-202003-56","refsource":"GENTOO","tags":[],"title":"Xen: Multiple vulnerabilities (GLSA 202003-56) — Gentoo security","mime":"text/html","httpstatus":"200","archivestatus":"200"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IZYATWNUGHRBG6I3TC24YHP5Y3J7I6KH/","name":"FEDORA-2019-cbb732f760","refsource":"","tags":[],"title":"[SECURITY] Fedora 30 Update: xen-4.11.2-3.fc30 - package-announce - Fedora Mailing-Lists","mime":"text/html","httpstatus":"200","archivestatus":"200"},{"url":"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2BQKX7M2RHCWDBKNPX4KEBI3MJIH6AYZ/","name":"FEDORA-2019-865bb16900","refsource":"","tags":[],"title":"[SECURITY] Fedora 29 Update: xen-4.11.2-2.fc29 - 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A malicious guest administrator may cause a hypervisor crash, resulting in a Denial of Service (DoS). Xen version 4.8 and newer are vulnerable. 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The rest of the code in the two functions will assume that there is a valid root table and check that with BUG_ON(). The function p2m_get_root_pointer() will ignore the unused top bits of a guest physical frame. This means that the function p2m_set_entry() will alias the frame. However, p2m->max_mapped_gfn will be updated using the original frame. It would be possible to set p2m->max_mapped_gfn high enough to cover a frame that would lead p2m_get_root_pointer() to return NULL in p2m_get_entry() and p2m_resolve_translation_fault(). Additionally, the sanity check on p2m->max_mapped_gfn is off-by-one allowing \"highest mapped + 1\" to be considered valid. However, p2m_get_root_pointer() will return NULL. The problem could be triggered with a specially crafted hypercall XENMEM_add_to_physmap{, _batch} followed by an access to an address (via hypercall or direct access) that passes the sanity check but cause p2m_get_root_pointer() to return NULL. A malicious guest administrator may cause a hypervisor crash, resulting in a Denial of Service (DoS). Xen version 4.8 and newer are vulnerable. Only Arm systems are vulnerable. x86 systems are not affected.","Type":"Description","Title":null},{"CveYear":"2019","CveId":"18423","Ordinal":"2","NoteData":"2019-10-31","Type":"Other","Title":"Published"},{"CveYear":"2019","CveId":"18423","Ordinal":"3","NoteData":"2020-03-26","Type":"Other","Title":"Modified"}]}}}