{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-31786", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-03-09T15:48:24.141Z", "datePublished": "2026-04-30T10:31:28.293Z", "dateUpdated": "2026-08-05T12:25:11.040Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:25:11.040Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nBuffer overflow in drivers/xen/sys-hypervisor.c\n\nThe build id returned by HYPERVISOR_xen_version(XENVER_build_id) is\nneither NUL terminated nor a string.\n\nThe first causes a buffer overflow as sprintf in buildid_show will\nread and copy till it finds a NUL.\n\n00000000 f4 91 51 f4 dd 38 9e 9d 65 47 52 eb 10 71 db 50 |..Q..8..eGR..q.P|\n00000010 b9 a8 01 42 6f 2e 32 |...Bo.2|\n00000017\n\nSo use a memcpy instead of sprintf to have the correct value:\n\n00000000 f4 91 51 f4 dd 00 9e 9d 65 47 52 eb 10 71 db 50 |..Q.....eGR..q.P|\n00000010 b9 a8 01 42 |...B|\n00000014\n\n(the above have a hack to embed a zero inside and check it's\nreturned correctly).\n\nThis is XSA-485 / CVE-2026-31786" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable buildid_show path is reached by a local read of /sys/hypervisor/properties/buildid inside a Linux Xen domain. It is not reachable directly from network packets or adjacent/physical interfaces.\nAC:L - Triggering the bug only requires reading a sysfs file, with no race or special timing. Any uncertainty about heap layout affects exploitation details, so the higher-severity low complexity is appropriate.\nPR:L - The sysfs attribute is read-only mode 0444, so any unprivileged local user in the Xen guest can access it. No capability, authentication, or real-root check gates the read path.\nUI:N - No victim action is required beyond the attacker performing the sysfs read. The vulnerable code runs synchronously in the attacker's read path.\nS:U - The impact is within the Linux Xen guest kernel security authority. This is not a Xen guest-to-host escape or cross-VM boundary violation.\nC:H - The bug performs an out-of-bounds read past the hypervisor build ID and can return adjacent kernel memory through a user-readable sysfs file. The Xen advisory states kernel secrets may be leaked.\nI:H - If no NUL byte is encountered before the PAGE_SIZE sysfs buffer is exceeded, sprintf can write past the sysfs buffer and corrupt kernel memory. The advisory identifies privilege escalation as possible, so high integrity impact is defensible.\nA:H - The out-of-bounds read/write can corrupt kernel memory and crash the guest kernel. The advisory explicitly lists DoS as a possible impact." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/xen/sys-hypervisor.c" ], "versions": [ { "version": "84b7625728ea311ea35bdaa0eded53c1c56baeaa", "lessThan": "e3af585e1728c917682b6a3de9a69b41fb9194d4", "status": "affected", "versionType": "git" }, { "version": "84b7625728ea311ea35bdaa0eded53c1c56baeaa", "lessThan": "8288d031a01dbacfde3fc643f7be3d23504de64d", "status": "affected", "versionType": "git" }, { "version": "84b7625728ea311ea35bdaa0eded53c1c56baeaa", "lessThan": "f458ba102da97fafca106327086fc95f3fc764cb", "status": "affected", "versionType": "git" }, { "version": "84b7625728ea311ea35bdaa0eded53c1c56baeaa", "lessThan": "4b4defd2fce3f966c25adabf46644a85558f1169", "status": "affected", "versionType": "git" }, { "version": "84b7625728ea311ea35bdaa0eded53c1c56baeaa", "lessThan": "5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0a", "status": "affected", "versionType": "git" }, { "version": "84b7625728ea311ea35bdaa0eded53c1c56baeaa", "lessThan": "d5f59216650c51e5e3fcb7517c825bc8047f60ef", "status": "affected", "versionType": "git" }, { "version": "84b7625728ea311ea35bdaa0eded53c1c56baeaa", "lessThan": "52cecff98bda2c51eed1c6ce9d21c5d6268fb19d", "status": "affected", "versionType": "git" }, { "version": "84b7625728ea311ea35bdaa0eded53c1c56baeaa", "lessThan": "27fdbab4221b375de54bf91919798d88520c6e28", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/xen/sys-hypervisor.c" ], "versions": [ { "version": "4.13", "status": "affected" }, { "version": "0", "lessThan": "4.13", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.254", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.204", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.170", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.137", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.85", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.26", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.3", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.13", "versionEndExcluding": "5.10.254" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.13", "versionEndExcluding": "5.15.204" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.13", "versionEndExcluding": "6.1.170" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.13", "versionEndExcluding": "6.6.137" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.13", "versionEndExcluding": "6.12.85" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.13", "versionEndExcluding": "6.18.26" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.13", "versionEndExcluding": "7.0.3" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.13", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/e3af585e1728c917682b6a3de9a69b41fb9194d4" }, { "url": "https://git.kernel.org/stable/c/8288d031a01dbacfde3fc643f7be3d23504de64d" }, { "url": "https://git.kernel.org/stable/c/f458ba102da97fafca106327086fc95f3fc764cb" }, { "url": "https://git.kernel.org/stable/c/4b4defd2fce3f966c25adabf46644a85558f1169" }, { "url": "https://git.kernel.org/stable/c/5c5ff7c7bd15bb536f44b10b3fb5b8408f344d0a" }, { "url": "https://git.kernel.org/stable/c/d5f59216650c51e5e3fcb7517c825bc8047f60ef" }, { "url": "https://git.kernel.org/stable/c/52cecff98bda2c51eed1c6ce9d21c5d6268fb19d" }, { "url": "https://git.kernel.org/stable/c/27fdbab4221b375de54bf91919798d88520c6e28" } ], "title": "Buffer overflow in drivers/xen/sys-hypervisor.c", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "http://www.openwall.com/lists/oss-security/2026/04/28/12" }, { "url": "http://xenbits.xen.org/xsa/advisory-485.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2026-04-30T10:39:32.708Z" } } ] } }