{"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":"2026-08-17T05:40:45.521Z"},"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"}}}}