{"api_version":"1","generated_at":"2026-09-16T11:06:35+00:00","cve":"CVE-2026-89793","urls":{"html":"https://cve.report/CVE-2026-89793","api":"https://cve.report/api/cve/CVE-2026-89793.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-89793","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-89793"},"summary":{"title":"ublk: clear VM_MAYWRITE on read-only ublk char device mmap","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nublk: clear VM_MAYWRITE on read-only ublk char device mmap\n\nublk_ch_mmap() rejects mmap requests with VM_WRITE set, but never\nclears VM_MAYWRITE on the resulting read-only mapping. This allows\na userspace daemon to mmap the per-queue command buffer PROT_READ,\nthen upgrade it to PROT_WRITE via mprotect(), since VM_MAYWRITE was\nnever cleared.\n\nThe command buffer holds struct ublksrv_io_desc entries that are\nkernel-written ABI; a writable mapping lets an unprivileged daemon\nprocess corrupt fields such as addr, op_flags, nr_sectors, and\nstart_sector.\n\nSame bug class as the drm/panthor and drm/vc4 VM_MAYWRITE fixes, and\nthe 2026-08-13 ptp/vmclock fix (a5edadbae57e).\n\nVerified via mprotect() PoC: before the fix, a PROT_READ mapping can\nbe upgraded to PROT_READ|PROT_WRITE and a write into the command\nbuffer corrupts io_desc fields (confirmed under KASAN). After the\nfix, mprotect() returns -EACCES.","state":"PUBLISHED","assigner":"Linux","published_at":"2026-09-16 10:16:55","updated_at":"2026-09-16 10:16:55"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/fa5e1bc673ca59722608af67b27e65dba0c97926","name":"https://git.kernel.org/stable/c/fa5e1bc673ca59722608af67b27e65dba0c97926","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/e373c1acdbcf88cec533ece9f589020adaed0a78","name":"https://git.kernel.org/stable/c/e373c1acdbcf88cec533ece9f589020adaed0a78","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/6e2b571b0a54755b06e092501913e1dfefe75d6c","name":"https://git.kernel.org/stable/c/6e2b571b0a54755b06e092501913e1dfefe75d6c","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/5befd06a72216869b607cf7724a4f16c6a2d3999","name":"https://git.kernel.org/stable/c/5befd06a72216869b607cf7724a4f16c6a2d3999","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/be41733c24be58e2a1ef718c80fafdfb98a40d5e","name":"https://git.kernel.org/stable/c/be41733c24be58e2a1ef718c80fafdfb98a40d5e","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-89793","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-89793","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 be41733c24be58e2a1ef718c80fafdfb98a40d5e git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 5befd06a72216869b607cf7724a4f16c6a2d3999 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 e373c1acdbcf88cec533ece9f589020adaed0a78 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 fa5e1bc673ca59722608af67b27e65dba0c97926 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 6e2b571b0a54755b06e092501913e1dfefe75d6c git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.6.157 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.12.110 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 6.18.51 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 7.2.5 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.157 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.110 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.51 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.2.5 7.2.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.3-rc2 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/block/ublk_drv.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"be41733c24be58e2a1ef718c80fafdfb98a40d5e","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"5befd06a72216869b607cf7724a4f16c6a2d3999","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"e373c1acdbcf88cec533ece9f589020adaed0a78","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"fa5e1bc673ca59722608af67b27e65dba0c97926","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"6e2b571b0a54755b06e092501913e1dfefe75d6c","status":"affected","version":"1da177e4c3f41524e886b7f1b8a0c1fc7321cac2","versionType":"git"},{"lessThan":"6.6.157","status":"affected","version":"0","versionType":"semver"},{"lessThan":"6.12.110","status":"affected","version":"0","versionType":"semver"},{"lessThan":"6.18.51","status":"affected","version":"0","versionType":"semver"},{"lessThan":"7.2.5","status":"affected","version":"0","versionType":"semver"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/block/ublk_drv.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.157","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.110","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.51","versionType":"semver"},{"lessThanOrEqual":"7.2.*","status":"unaffected","version":"7.2.5","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.3-rc2","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.157","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.110","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.51","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.2.5","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.3-rc2","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nublk: clear VM_MAYWRITE on read-only ublk char device mmap\n\nublk_ch_mmap() rejects mmap requests with VM_WRITE set, but never\nclears VM_MAYWRITE on the resulting read-only mapping. This allows\na userspace daemon to mmap the per-queue command buffer PROT_READ,\nthen upgrade it to PROT_WRITE via mprotect(), since VM_MAYWRITE was\nnever cleared.\n\nThe command buffer holds struct ublksrv_io_desc entries that are\nkernel-written ABI; a writable mapping lets an unprivileged daemon\nprocess corrupt fields such as addr, op_flags, nr_sectors, and\nstart_sector.\n\nSame bug class as the drm/panthor and drm/vc4 VM_MAYWRITE fixes, and\nthe 2026-08-13 ptp/vmclock fix (a5edadbae57e).\n\nVerified via mprotect() PoC: before the fix, a PROT_READ mapping can\nbe upgraded to PROT_READ|PROT_WRITE and a write into the command\nbuffer corrupts io_desc fields (confirmed under KASAN). After the\nfix, mprotect() returns -EACCES."}],"providerMetadata":{"dateUpdated":"2026-09-16T09:54:33.678Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/be41733c24be58e2a1ef718c80fafdfb98a40d5e"},{"url":"https://git.kernel.org/stable/c/5befd06a72216869b607cf7724a4f16c6a2d3999"},{"url":"https://git.kernel.org/stable/c/e373c1acdbcf88cec533ece9f589020adaed0a78"},{"url":"https://git.kernel.org/stable/c/fa5e1bc673ca59722608af67b27e65dba0c97926"},{"url":"https://git.kernel.org/stable/c/6e2b571b0a54755b06e092501913e1dfefe75d6c"}],"title":"ublk: clear VM_MAYWRITE on read-only ublk char device mmap","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-89793","datePublished":"2026-09-16T09:54:33.678Z","dateReserved":"2026-09-11T19:38:34.766Z","dateUpdated":"2026-09-16T09:54:33.678Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-09-16 10:16:55","lastModifiedDate":"2026-09-16 10:16:55","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"89793","Ordinal":"1","Title":"ublk: clear VM_MAYWRITE on read-only ublk char device mmap","CVE":"CVE-2026-89793","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"89793","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\nublk: clear VM_MAYWRITE on read-only ublk char device mmap\n\nublk_ch_mmap() rejects mmap requests with VM_WRITE set, but never\nclears VM_MAYWRITE on the resulting read-only mapping. This allows\na userspace daemon to mmap the per-queue command buffer PROT_READ,\nthen upgrade it to PROT_WRITE via mprotect(), since VM_MAYWRITE was\nnever cleared.\n\nThe command buffer holds struct ublksrv_io_desc entries that are\nkernel-written ABI; a writable mapping lets an unprivileged daemon\nprocess corrupt fields such as addr, op_flags, nr_sectors, and\nstart_sector.\n\nSame bug class as the drm/panthor and drm/vc4 VM_MAYWRITE fixes, and\nthe 2026-08-13 ptp/vmclock fix (a5edadbae57e).\n\nVerified via mprotect() PoC: before the fix, a PROT_READ mapping can\nbe upgraded to PROT_READ|PROT_WRITE and a write into the command\nbuffer corrupts io_desc fields (confirmed under KASAN). After the\nfix, mprotect() returns -EACCES.","Type":"Description","Title":"ublk: clear VM_MAYWRITE on read-only ublk char device mmap"}]}}}