{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-80724", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-26T14:34:25.788Z", "datePublished": "2026-08-28T07:03:08.410Z", "dateUpdated": "2026-10-19T08:43:13.410Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T08:43:13.410Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nptp: vmclock: prevent read-only mappings from becoming writable\n\nvmclock_miscdev_mmap() rejects writable mappings of the shared vmclock\nABI page with -EROFS, but leaves VM_MAYWRITE set. Userspace can map the\npage read-only and then upgrade it to writable with mprotect(), after\nwhich the guest can corrupt the host-written timekeeping data (sequence\ncounter, UTC time, TSC offset) that the vmclock ABI defines as read-only.\n\nClear VM_MAYWRITE on the read-only path so the mapping cannot be\nupgraded, as i915 does for its read-only objects and as fixed in drm/vc4\n(CVE-2026-68445) and drm/panthor (CVE-2024-53071)." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 8.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - Exploitation requires local syscalls to open /dev/vmclock0, mmap the shared ABI page read-only, mprotect it writable, and write host-authoritative fields; there is no network, Bluetooth, or physical-device path to vmclock_miscdev_mmap().\nAC:L - Any process that can open the misc device can reliably mmap(PROT_READ), mprotect(PROT_WRITE), and corrupt the page without races, special memory layout, or timing; VM_MAYWRITE left set is the sole missing check and mprotect honors it per mm/mprotect.c.\nPR:L - vmclock_miscdev_open() performs no capability checks; AWS ClockBound documents chmod a+r on /dev/vmclock0 for unprivileged latency-sensitive apps on EC2/Amazon Linux, so a normal tenant user on affected cloud VMs can reach the bug without root or user-namespace admin caps.\nUI:N - The attacker process performs the full open/mmap/mprotect/write sequence itself; no victim mount, click, or other user action is required beyond the attacker already having local shell access.\nS:C - The vmclock ABI page is hypervisor-written shared memory whose seq_count, UTC time, and TSC offset must stay guest-read-only; mprotect bypass lets a guest user corrupt that host-authoritative data, crossing the guest/hypervisor trust boundary rather than staying within guest-kernel scope alone.\nC:H - Unauthorized writes let an attacker race seq_count updates and corrupt in-flight host-populated fields, yielding torn reads of timekeeping data to other guest consumers and potentially exposing transient host-written values that read-only mmap alone would not reliably observe.\nI:H - After mprotect, the attacker gains arbitrary modification of host-written vmclock_abi fields (seq_count, disruption_marker, counter_value, time_sec, flags), breaking integrity of authoritative timekeeping and migration/disruption signaling relied on by guest kernel PTP and userspace ClockBound consumers.\nA:H - Corrupting seq_count, clock_status, or disruption/vm_generation markers can force ETIMEDOUT/-EINVAL in vmclock_get_crosststamp, trigger false migration/disruption handling, and cause latency-sensitive services to withdraw or fail, producing severe availability loss on affected cloud VMs." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/ptp/ptp_vmclock.c" ], "versions": [ { "version": "20503272422693d793b84f88bf23fe4e955d3a33", "lessThan": "5b4f2bec7bea6c04084d720d731bedee7caf878d", "status": "affected", "versionType": "git" }, { "version": "20503272422693d793b84f88bf23fe4e955d3a33", "lessThan": "3f5677d2f817355147337f0453174c7bb0f3b66a", "status": "affected", "versionType": "git" }, { "version": "20503272422693d793b84f88bf23fe4e955d3a33", "lessThan": "2496e141827102d6af512950057d402a2cfb2bfc", "status": "affected", "versionType": "git" }, { "version": "20503272422693d793b84f88bf23fe4e955d3a33", "lessThan": "2e596e7814ba38cdc129991058b6c254ed37cb11", "status": "affected", "versionType": "git" }, { "version": "20503272422693d793b84f88bf23fe4e955d3a33", "lessThan": "0ce59c4148ecd1520c5592a63bb3c8991ee2d326", "status": "affected", "versionType": "git" }, { "version": "20503272422693d793b84f88bf23fe4e955d3a33", "lessThan": "a5edadbae57e2298a56cf7a4e774a027905a331f", "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/ptp/ptp_vmclock.c" ], "versions": [ { "version": "6.13", "status": "affected" }, { "version": "0", "lessThan": "6.13", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.47", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.50", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.11", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.1", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.4", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "6.13", "versionEndExcluding": "6.18.47" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "6.18.50" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "7.1.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "7.2.1" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "7.2.4" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.13", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/5b4f2bec7bea6c04084d720d731bedee7caf878d" }, { "url": "https://git.kernel.org/stable/c/3f5677d2f817355147337f0453174c7bb0f3b66a" }, { "url": "https://git.kernel.org/stable/c/2496e141827102d6af512950057d402a2cfb2bfc" }, { "url": "https://git.kernel.org/stable/c/2e596e7814ba38cdc129991058b6c254ed37cb11" }, { "url": "https://git.kernel.org/stable/c/0ce59c4148ecd1520c5592a63bb3c8991ee2d326" }, { "url": "https://git.kernel.org/stable/c/a5edadbae57e2298a56cf7a4e774a027905a331f" } ], "title": "ptp: vmclock: prevent read-only mappings from becoming writable", "x_generator": { "engine": "bippy-1.2.0" } } } }