{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72135", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.907Z", "datePublished": "2026-08-15T05:53:10.315Z", "dateUpdated": "2026-10-16T18:44:58.643Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:40:45.521Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntpm: Make the TPM character devices non-seekable\n\nThe TPM character devices expose a sequential command/response\ninterface, but their open handlers leave FMODE_PREAD and FMODE_PWRITE\nenabled.\n\nAfter a command leaves a response pending, pread(fd, buf, 16, 0x1400)\npasses 0x1400 as *off to tpm_common_read(). The transfer length is\nbounded by response_length, but the offset is used unchecked when\nforming data_buffer + *off. A sufficiently large offset therefore causes\nan out-of-bounds heap read through copy_to_user() and, if the copy\nsucceeds, an out-of-bounds zero-write through the following memset().\n\nPositional I/O does not provide coherent semantics for this interface.\nAn arbitrary pread offset cannot represent how much of a response has\nbeen consumed sequentially. The write callback always stores a command\nat the start of data_buffer, while pwrite() does not update file->f_pos\nand can leave the sequential read cursor stale.\n\nCall nonseekable_open() from both open handlers. This removes\nFMODE_PREAD and FMODE_PWRITE, causing positional reads and writes to\nfail with -ESPIPE before reaching the TPM callbacks, and explicitly\nmarks the files non-seekable. Normal read() and write() continue to use\nthe existing sequential f_pos cursor, leaving the response state machine\nunchanged.\n\nTested on Linux 6.12 with KASAN and a swtpm TPM2 device:\n\n - sequential partial reads returned the complete response\n - pread() and preadv() with offset 0x1400 returned -ESPIPE\n - pwrite() and pwritev() with offset zero returned -ESPIPE\n - the pending response remained intact after the rejected operations\n - a subsequent normal command/response cycle completed normally\n - no KASAN report was produced." } ], "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 pread()/write() syscalls on /dev/tpm0 or /dev/tpmrm0 character devices; there is no network, Bluetooth, or physical-bus code path to the vulnerable tpm_common_read() handler.\nAC:L - An attacker who can open the device reliably triggers the bug by writing any TPM command to create a pending response, then calling pread() with a large offset; no races or special memory layout are required.\nPR:L - Upstream tpm2-tss udev rules grant non-root users in the tss group read/write access to /dev/tpmrm0 (mode 0660), which is the standard TPM2 user-space interface on laptops and servers with TPM hardware.\nUI:N - No victim interaction is required; the attacker opens the TPM device, submits a command, and issues the malicious pread() themselves without relying on another user to mount, click, or configure anything.\nS:U - The vulnerability corrupts kernel heap memory in the TPM driver on the same host; it does not by itself cross a VM, container, or IOMMU security boundary to affect a different trust domain.\nC:H - Unchecked pread offsets cause copy_to_user() to read beyond the 4096-byte data_buffer into adjacent kmalloc slab memory (including tpm_space pointers), leaking kernel heap contents to userspace.\nI:H - A successful out-of-bounds pread also executes memset() past data_buffer, zeroing adjacent heap objects such as tpm_space session/context pointers and enabling further memory corruption or control-flow manipulation.\nA:H - KASAN reports slab-out-of-bounds faults on both the copy_to_user read and memset write; corrupting adjacent heap structures can oops or panic the kernel during subsequent TPM operations." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/char/tpm/tpm-dev.c", "drivers/char/tpm/tpmrm-dev.c" ], "versions": [ { "version": "9488585b21bef0df1217e510c7134905d1d376a7", "lessThan": "ed0ffc2c016629e40ba041ed0424a772d8b02e2c", "status": "affected", "versionType": "git" }, { "version": "9488585b21bef0df1217e510c7134905d1d376a7", "lessThan": "232dcf908eb7eb9d8046a9597975caf44270966e", "status": "affected", "versionType": "git" }, { "version": "9488585b21bef0df1217e510c7134905d1d376a7", "lessThan": "dda695fab5e21f923d29e8cb01df256468ddfbd1", "status": "affected", "versionType": "git" }, { "version": "9488585b21bef0df1217e510c7134905d1d376a7", "lessThan": "9c513dabd4540f811585a2087f23069767a284da", "status": "affected", "versionType": "git" }, { "version": "9488585b21bef0df1217e510c7134905d1d376a7", "lessThan": "21a13f932972bc9836f58c44fcd47c62abdecd95", "status": "affected", "versionType": "git" }, { "version": "9488585b21bef0df1217e510c7134905d1d376a7", "lessThan": "ada4b9a5087ea7f30dd8e4c6411a4fb6547eb1ed", "status": "affected", "versionType": "git" }, { "version": "9488585b21bef0df1217e510c7134905d1d376a7", "lessThan": "947b773caaa548672184df025271b29bdc80b0f1", "status": "affected", "versionType": "git" }, { "version": "9488585b21bef0df1217e510c7134905d1d376a7", "lessThan": "f20d61c22bcaf172d6790b6500e3838e532e71c8", "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/char/tpm/tpm-dev.c", "drivers/char/tpm/tpmrm-dev.c" ], "versions": [ { "version": "5.0", "status": "affected" }, { "version": "0", "lessThan": "5.0", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.261", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.212", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.178", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.145", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.97", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.40", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2", "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": "5.0", "versionEndExcluding": "5.10.261" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "5.15.212" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.1.178" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.6.145" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.0", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/ed0ffc2c016629e40ba041ed0424a772d8b02e2c" }, { "url": "https://git.kernel.org/stable/c/232dcf908eb7eb9d8046a9597975caf44270966e" }, { "url": "https://git.kernel.org/stable/c/dda695fab5e21f923d29e8cb01df256468ddfbd1" }, { "url": "https://git.kernel.org/stable/c/9c513dabd4540f811585a2087f23069767a284da" }, { "url": "https://git.kernel.org/stable/c/21a13f932972bc9836f58c44fcd47c62abdecd95" }, { "url": "https://git.kernel.org/stable/c/ada4b9a5087ea7f30dd8e4c6411a4fb6547eb1ed" }, { "url": "https://git.kernel.org/stable/c/947b773caaa548672184df025271b29bdc80b0f1" }, { "url": "https://git.kernel.org/stable/c/f20d61c22bcaf172d6790b6500e3838e532e71c8" } ], "title": "tpm: Make the TPM character devices non-seekable", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2026-72135", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2026-10-16T18:42:38.338660Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-10-16T18:44:58.643Z" } } ] } }