{"api_version":"1","generated_at":"2026-08-02T14:48:49+00:00","cve":"CVE-2026-64527","urls":{"html":"https://cve.report/CVE-2026-64527","api":"https://cve.report/api/cve/CVE-2026-64527.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-64527","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64527"},"summary":{"title":"drm/hyperv: validate VMBus packet size in receive callback","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/hyperv: validate VMBus packet size in receive callback\n\nhyperv_receive_sub() reads msg->vid_hdr.type and dispatches into one\nof four message-type branches without knowing how many bytes the host\nwrote into hv->recv_buf. The completion path then runs\nmemcpy(hv->init_buf, msg, VMBUS_MAX_PACKET_SIZE), so the consumer that\nwakes on wait_for_completion_timeout() can read up to 16 KiB of\nresidue from a prior message as if it were the response payload.\n\nPass bytes_recvd into hyperv_receive_sub() and reject any packet that\ndoes not cover the pipe + synthvid header. A single switch on\nmsg->vid_hdr.type then computes the type-specific payload size: the\nthree completion-driving types (SYNTHVID_VERSION_RESPONSE,\nSYNTHVID_RESOLUTION_RESPONSE, SYNTHVID_VRAM_LOCATION_ACK) fall through\nto a shared exit that requires that size before memcpy/complete, while\nSYNTHVID_FEATURE_CHANGE validates its own payload and returns before\nreading is_dirt_needed. Unknown types are dropped.\n\nSYNTHVID_RESOLUTION_RESPONSE is variable length: the host fills\nresolution_count entries, not the full SYNTHVID_MAX_RESOLUTION_COUNT\narray. Validate the fixed prefix first so resolution_count can be\nread, bound it against the array, then require only the count-sized\narray, so the shorter responses the host actually sends are accepted.\n\nOnly run the sub-handler when vmbus_recvpacket() returned success. The\nmemcpy length is bytes_recvd, which is bounded by VMBUS_MAX_PACKET_SIZE\nonly on a successful receive; on -ENOBUFS vmbus_recvpacket() instead\nreports the required length, which can exceed hv->recv_buf, so copying\nbytes_recvd would read and write past the 16 KiB buffers. Gating on the\nsuccess return keeps the copy bounded. The nonzero-return path is itself\na malformed-message case and is now logged rather than silently skipped;\nchannel recovery is not attempted.\n\nRejected packets are reported via drm_err_ratelimited() rather than\nsilently dropped, matching the CoCo-hardened pattern in\nhv_kvp_onchannelcallback().","state":"PUBLISHED","assigner":"Linux","published_at":"2026-07-25 10:17:39","updated_at":"2026-07-25 10:17:39"},"problem_types":[],"metrics":[],"references":[{"url":"https://git.kernel.org/stable/c/7f87763f47a3c22fb50265a00619ef10f2394b18","name":"https://git.kernel.org/stable/c/7f87763f47a3c22fb50265a00619ef10f2394b18","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/f5251226551bfec98c4705641b6f94ff1f238d91","name":"https://git.kernel.org/stable/c/f5251226551bfec98c4705641b6f94ff1f238d91","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/588c84b461393ff1998ac7b97b04f953f642e0df","name":"https://git.kernel.org/stable/c/588c84b461393ff1998ac7b97b04f953f642e0df","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/164dc7bf17609340233c6bf4f66bb7c7008a0511","name":"https://git.kernel.org/stable/c/164dc7bf17609340233c6bf4f66bb7c7008a0511","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/049a6b474823049fe60212f25f26e4b30f44ee8f","name":"https://git.kernel.org/stable/c/049a6b474823049fe60212f25f26e4b30f44ee8f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/c8974d96b6a5496f33dc69a3ce28a7bf5078def4","name":"https://git.kernel.org/stable/c/c8974d96b6a5496f33dc69a3ce28a7bf5078def4","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://git.kernel.org/stable/c/57d5d697642e05d5dd2d40660817765943dd709f","name":"https://git.kernel.org/stable/c/57d5d697642e05d5dd2d40660817765943dd709f","refsource":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-64527","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64527","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 76c56a5affeba1e163b66b9d8cc192e6154466f0 57d5d697642e05d5dd2d40660817765943dd709f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 76c56a5affeba1e163b66b9d8cc192e6154466f0 f5251226551bfec98c4705641b6f94ff1f238d91 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 76c56a5affeba1e163b66b9d8cc192e6154466f0 049a6b474823049fe60212f25f26e4b30f44ee8f git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 76c56a5affeba1e163b66b9d8cc192e6154466f0 588c84b461393ff1998ac7b97b04f953f642e0df git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 76c56a5affeba1e163b66b9d8cc192e6154466f0 164dc7bf17609340233c6bf4f66bb7c7008a0511 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 76c56a5affeba1e163b66b9d8cc192e6154466f0 c8974d96b6a5496f33dc69a3ce28a7bf5078def4 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 76c56a5affeba1e163b66b9d8cc192e6154466f0 7f87763f47a3c22fb50265a00619ef10f2394b18 git","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"affected 5.14","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.14 semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 5.15.210 5.15.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.1.176 6.1.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.6.143 6.6.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.12.93 6.12.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 6.18.35 6.18.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.0.12 7.0.* semver","platforms":[]},{"source":"CNA","vendor":"Linux","product":"Linux","version":"unaffected 7.1 * original_commit_for_fix","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":{"cve_year":"2026","cve_id":"64527","cve":"CVE-2026-64527","epss":"0.001610000","percentile":"0.056620000","score_date":"2026-07-29","updated_at":"2026-07-30 00:09:16"},"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"defaultStatus":"unaffected","product":"Linux","programFiles":["drivers/gpu/drm/hyperv/hyperv_drm_proto.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"lessThan":"57d5d697642e05d5dd2d40660817765943dd709f","status":"affected","version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","versionType":"git"},{"lessThan":"f5251226551bfec98c4705641b6f94ff1f238d91","status":"affected","version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","versionType":"git"},{"lessThan":"049a6b474823049fe60212f25f26e4b30f44ee8f","status":"affected","version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","versionType":"git"},{"lessThan":"588c84b461393ff1998ac7b97b04f953f642e0df","status":"affected","version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","versionType":"git"},{"lessThan":"164dc7bf17609340233c6bf4f66bb7c7008a0511","status":"affected","version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","versionType":"git"},{"lessThan":"c8974d96b6a5496f33dc69a3ce28a7bf5078def4","status":"affected","version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","versionType":"git"},{"lessThan":"7f87763f47a3c22fb50265a00619ef10f2394b18","status":"affected","version":"76c56a5affeba1e163b66b9d8cc192e6154466f0","versionType":"git"}]},{"defaultStatus":"affected","product":"Linux","programFiles":["drivers/gpu/drm/hyperv/hyperv_drm_proto.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","vendor":"Linux","versions":[{"status":"affected","version":"5.14"},{"lessThan":"5.14","status":"unaffected","version":"0","versionType":"semver"},{"lessThanOrEqual":"5.15.*","status":"unaffected","version":"5.15.210","versionType":"semver"},{"lessThanOrEqual":"6.1.*","status":"unaffected","version":"6.1.176","versionType":"semver"},{"lessThanOrEqual":"6.6.*","status":"unaffected","version":"6.6.143","versionType":"semver"},{"lessThanOrEqual":"6.12.*","status":"unaffected","version":"6.12.93","versionType":"semver"},{"lessThanOrEqual":"6.18.*","status":"unaffected","version":"6.18.35","versionType":"semver"},{"lessThanOrEqual":"7.0.*","status":"unaffected","version":"7.0.12","versionType":"semver"},{"lessThanOrEqual":"*","status":"unaffected","version":"7.1","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"cpeMatch":[{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"5.15.210","versionStartIncluding":"5.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.1.176","versionStartIncluding":"5.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.6.143","versionStartIncluding":"5.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.12.93","versionStartIncluding":"5.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"6.18.35","versionStartIncluding":"5.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.0.12","versionStartIncluding":"5.14","vulnerable":true},{"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionEndExcluding":"7.1","versionStartIncluding":"5.14","vulnerable":true}],"negate":false,"operator":"OR"}]}],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/hyperv: validate VMBus packet size in receive callback\n\nhyperv_receive_sub() reads msg->vid_hdr.type and dispatches into one\nof four message-type branches without knowing how many bytes the host\nwrote into hv->recv_buf. The completion path then runs\nmemcpy(hv->init_buf, msg, VMBUS_MAX_PACKET_SIZE), so the consumer that\nwakes on wait_for_completion_timeout() can read up to 16 KiB of\nresidue from a prior message as if it were the response payload.\n\nPass bytes_recvd into hyperv_receive_sub() and reject any packet that\ndoes not cover the pipe + synthvid header. A single switch on\nmsg->vid_hdr.type then computes the type-specific payload size: the\nthree completion-driving types (SYNTHVID_VERSION_RESPONSE,\nSYNTHVID_RESOLUTION_RESPONSE, SYNTHVID_VRAM_LOCATION_ACK) fall through\nto a shared exit that requires that size before memcpy/complete, while\nSYNTHVID_FEATURE_CHANGE validates its own payload and returns before\nreading is_dirt_needed. Unknown types are dropped.\n\nSYNTHVID_RESOLUTION_RESPONSE is variable length: the host fills\nresolution_count entries, not the full SYNTHVID_MAX_RESOLUTION_COUNT\narray. Validate the fixed prefix first so resolution_count can be\nread, bound it against the array, then require only the count-sized\narray, so the shorter responses the host actually sends are accepted.\n\nOnly run the sub-handler when vmbus_recvpacket() returned success. The\nmemcpy length is bytes_recvd, which is bounded by VMBUS_MAX_PACKET_SIZE\nonly on a successful receive; on -ENOBUFS vmbus_recvpacket() instead\nreports the required length, which can exceed hv->recv_buf, so copying\nbytes_recvd would read and write past the 16 KiB buffers. Gating on the\nsuccess return keeps the copy bounded. The nonzero-return path is itself\na malformed-message case and is now logged rather than silently skipped;\nchannel recovery is not attempted.\n\nRejected packets are reported via drm_err_ratelimited() rather than\nsilently dropped, matching the CoCo-hardened pattern in\nhv_kvp_onchannelcallback()."}],"providerMetadata":{"dateUpdated":"2026-07-25T09:20:51.078Z","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux"},"references":[{"url":"https://git.kernel.org/stable/c/57d5d697642e05d5dd2d40660817765943dd709f"},{"url":"https://git.kernel.org/stable/c/f5251226551bfec98c4705641b6f94ff1f238d91"},{"url":"https://git.kernel.org/stable/c/049a6b474823049fe60212f25f26e4b30f44ee8f"},{"url":"https://git.kernel.org/stable/c/588c84b461393ff1998ac7b97b04f953f642e0df"},{"url":"https://git.kernel.org/stable/c/164dc7bf17609340233c6bf4f66bb7c7008a0511"},{"url":"https://git.kernel.org/stable/c/c8974d96b6a5496f33dc69a3ce28a7bf5078def4"},{"url":"https://git.kernel.org/stable/c/7f87763f47a3c22fb50265a00619ef10f2394b18"}],"title":"drm/hyperv: validate VMBus packet size in receive callback","x_generator":{"engine":"bippy-1.2.0"}}},"cveMetadata":{"assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","assignerShortName":"Linux","cveId":"CVE-2026-64527","datePublished":"2026-07-25T09:20:51.078Z","dateReserved":"2026-07-19T15:36:31.794Z","dateUpdated":"2026-07-25T09:20:51.078Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-07-25 10:17:39","lastModifiedDate":"2026-07-25 10:17:39","problem_types":[],"metrics":[],"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"64527","Ordinal":"1","Title":"drm/hyperv: validate VMBus packet size in receive callback","CVE":"CVE-2026-64527","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"64527","Ordinal":"1","NoteData":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm/hyperv: validate VMBus packet size in receive callback\n\nhyperv_receive_sub() reads msg->vid_hdr.type and dispatches into one\nof four message-type branches without knowing how many bytes the host\nwrote into hv->recv_buf. The completion path then runs\nmemcpy(hv->init_buf, msg, VMBUS_MAX_PACKET_SIZE), so the consumer that\nwakes on wait_for_completion_timeout() can read up to 16 KiB of\nresidue from a prior message as if it were the response payload.\n\nPass bytes_recvd into hyperv_receive_sub() and reject any packet that\ndoes not cover the pipe + synthvid header. A single switch on\nmsg->vid_hdr.type then computes the type-specific payload size: the\nthree completion-driving types (SYNTHVID_VERSION_RESPONSE,\nSYNTHVID_RESOLUTION_RESPONSE, SYNTHVID_VRAM_LOCATION_ACK) fall through\nto a shared exit that requires that size before memcpy/complete, while\nSYNTHVID_FEATURE_CHANGE validates its own payload and returns before\nreading is_dirt_needed. Unknown types are dropped.\n\nSYNTHVID_RESOLUTION_RESPONSE is variable length: the host fills\nresolution_count entries, not the full SYNTHVID_MAX_RESOLUTION_COUNT\narray. Validate the fixed prefix first so resolution_count can be\nread, bound it against the array, then require only the count-sized\narray, so the shorter responses the host actually sends are accepted.\n\nOnly run the sub-handler when vmbus_recvpacket() returned success. The\nmemcpy length is bytes_recvd, which is bounded by VMBUS_MAX_PACKET_SIZE\nonly on a successful receive; on -ENOBUFS vmbus_recvpacket() instead\nreports the required length, which can exceed hv->recv_buf, so copying\nbytes_recvd would read and write past the 16 KiB buffers. Gating on the\nsuccess return keeps the copy bounded. The nonzero-return path is itself\na malformed-message case and is now logged rather than silently skipped;\nchannel recovery is not attempted.\n\nRejected packets are reported via drm_err_ratelimited() rather than\nsilently dropped, matching the CoCo-hardened pattern in\nhv_kvp_onchannelcallback().","Type":"Description","Title":"drm/hyperv: validate VMBus packet size in receive callback"}]}}}