{"id":"CVE-2026-68445","state":"PUBLISHED","title":"drm/vc4: Prevent shader BO mappings from becoming writable","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/vc4: Prevent shader BO mappings from becoming writable\n\nvc4_gem_object_mmap() rejects a writable mapping of a validated shader\nBO, but leaves VM_MAYWRITE set.  Userspace can map the BO read-only and\nthen turn it writable with mprotect().\n\nValidated shader BOs must stay read-only: the validator checks the\ninstructions once and the GPU trusts them afterwards.  A writable\nmapping lets userspace rewrite the code after validation, bypassing the\nvalidator.\n\nClear VM_MAYWRITE on the read-only path so the mapping cannot be\nupgraded, as i915 already does for its read-only objects.","publishedAt":"2026-08-12T00:07:36.230Z","updatedAt":"2026-10-30T12:28:38.418Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"4c98260a967e8536c69437b8da8eea3188cd6db8","versionType":"git"},{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"9f0ee411fc2d76333d6087c5862ffa907cf7a175","versionType":"git"},{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"019e6ad247f7fd038d2e009789f6d9bfcccb1ae7","versionType":"git"},{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"6deaa317201851c644c431b57682e54d06b35838","versionType":"git"},{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"fe168ef1d232d734d9998fd74822e2e20930dfff","versionType":"git"},{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"0c9e6367639548307d3f578f6943ce72c9d39087","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/vc4/vc4_bo.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.5","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.5","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/vc4/vc4_bo.c"]}],"references":["https://git.kernel.org/stable/c/4c98260a967e8536c69437b8da8eea3188cd6db8","https://git.kernel.org/stable/c/9f0ee411fc2d76333d6087c5862ffa907cf7a175","https://git.kernel.org/stable/c/019e6ad247f7fd038d2e009789f6d9bfcccb1ae7","https://git.kernel.org/stable/c/6deaa317201851c644c431b57682e54d06b35838","https://git.kernel.org/stable/c/fe168ef1d232d734d9998fd74822e2e20930dfff","https://git.kernel.org/stable/c/0c9e6367639548307d3f578f6943ce72c9d39087"],"weaknesses":[],"ingestedAt":"2026-10-30T12:46:06.359Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/68xxx/CVE-2026-68445.json","commit":"1f312381e38164a43607eebab851b151dd16861e","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-68445","state":"PUBLISHED","datePublished":"2026-08-12T00:07:36.230Z","dateUpdated":"2026-10-30T12:28:38.418Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-07-30T09:28:09.394Z"},"containers":{"cna":{"title":"drm/vc4: Prevent shader BO mappings from becoming writable","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/vc4: Prevent shader BO mappings from becoming writable\n\nvc4_gem_object_mmap() rejects a writable mapping of a validated shader\nBO, but leaves VM_MAYWRITE set.  Userspace can map the BO read-only and\nthen turn it writable with mprotect().\n\nValidated shader BOs must stay read-only: the validator checks the\ninstructions once and the GPU trusts them afterwards.  A writable\nmapping lets userspace rewrite the code after validation, bypassing the\nvalidator.\n\nClear VM_MAYWRITE on the read-only path so the mapping cannot be\nupgraded, as i915 already does for its read-only objects."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"4c98260a967e8536c69437b8da8eea3188cd6db8","versionType":"git"},{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"9f0ee411fc2d76333d6087c5862ffa907cf7a175","versionType":"git"},{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"019e6ad247f7fd038d2e009789f6d9bfcccb1ae7","versionType":"git"},{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"6deaa317201851c644c431b57682e54d06b35838","versionType":"git"},{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"fe168ef1d232d734d9998fd74822e2e20930dfff","versionType":"git"},{"version":"463873d5701427f2964a0b4b72c45f1f14b6df87","status":"affected","lessThan":"0c9e6367639548307d3f578f6943ce72c9d39087","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/vc4/vc4_bo.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.5","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.5","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.148","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.101","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.42","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"7.1.6","status":"unaffected","lessThanOrEqual":"7.1.*","versionType":"semver"},{"version":"7.2","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/vc4/vc4_bo.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/4c98260a967e8536c69437b8da8eea3188cd6db8"},{"url":"https://git.kernel.org/stable/c/9f0ee411fc2d76333d6087c5862ffa907cf7a175"},{"url":"https://git.kernel.org/stable/c/019e6ad247f7fd038d2e009789f6d9bfcccb1ae7"},{"url":"https://git.kernel.org/stable/c/6deaa317201851c644c431b57682e54d06b35838"},{"url":"https://git.kernel.org/stable/c/fe168ef1d232d734d9998fd74822e2e20930dfff"},{"url":"https://git.kernel.org/stable/c/0c9e6367639548307d3f578f6943ce72c9d39087"}],"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 - Exploitation requires local access to the vc4 DRM render node (/dev/dri/renderD*) to issue VC4_CREATE_SHADER_BO, VC4_MMAP_BO, mmap/mprotect and VC4_SUBMIT_CL; there is no remote or network-facing path to this code.\nAC:L - The attacker fully controls every step: create a shader that passes validation, map it PROT_READ, upgrade it with mprotect(PROT_WRITE), rewrite the instructions and submit. There is no race, no memory-layout dependency, and it works on the default configuration of any VC4 (Raspberry Pi) system.\nPR:L - VC4_CREATE_SHADER_BO, VC4_MMAP_BO and VC4_SUBMIT_CL are all DRM_RENDER_ALLOW ioctls, so an ordinary unprivileged user with render-node access (the default for logged-in/graphical users on Raspberry Pi and embedded VC4 devices) can perform the whole sequence. No capability check is involved.\nUI:N - The attacking process performs the entire sequence itself; no action by another user or administrator is needed.\nS:U - The vulnerable driver and the compromised resource (kernel/system memory) are both under the kernel's security authority; this is a standard local kernel privilege escalation rather than a VM or hypervisor boundary escape.\nC:H - Post-validation rewriting of shader code lets the GPU, which has no IOMMU on VC4, read arbitrary system memory via texture, uniform and direct-addressed TMU lookups — exactly the disclosure the validator exists to prevent, giving arbitrary kernel memory read.\nI:H - Unvalidated QPU code can use the VPM write address register in general-purpose DMA mode to write to arbitrary physical addresses, an arbitrary kernel-memory write primitive that yields full privilege escalation and code execution.\nA:H - The same arbitrary DMA writes and unbounded shader execution readily corrupt kernel structures or hang the GPU, causing kernel panics or a full system hang triggerable at will by an unprivileged user."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:28:38.418Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.5","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.5","versionEndExcluding":"6.6.148"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.5","versionEndExcluding":"6.12.101"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.5","versionEndExcluding":"6.18.42"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.5","versionEndExcluding":"7.1.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.5","versionEndExcluding":"7.2"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}}}}}