{"id":"CVE-2026-72135","title":"tpm: Make the TPM character devices non-seekable","summary":"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 an…","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < ed0ffc2c016629e40ba041ed0424a772d8b02e2c","Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < 232dcf908eb7eb9d8046a9597975caf44270966e","Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < dda695fab5e21f923d29e8cb01df256468ddfbd1","Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < 9c513dabd4540f811585a2087f23069767a284da","Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < 21a13f932972bc9836f58c44fcd47c62abdecd95","Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < ada4b9a5087ea7f30dd8e4c6411a4fb6547eb1ed","Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < 947b773caaa548672184df025271b29bdc80b0f1","Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < f20d61c22bcaf172d6790b6500e3838e532e71c8","Linux 5.0"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"total","timestamp":"2026-10-16T18:42:38.338660Z"},"published":"2026-08-15","updated":"2026-10-16","sourceUpdated":"2026-10-16T18:44:58.643Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-72135","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"}],"tags":["cve.org"],"epss":0.00169,"epssPercentile":0.05787,"ingestedAt":"2026-10-16T19:46:24.428Z","slug":"CVE-2026-72135","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < ed0ffc2c016629e40ba041ed0424a772d8b02e2c`\n- `Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < 232dcf908eb7eb9d8046a9597975caf44270966e`\n- `Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < dda695fab5e21f923d29e8cb01df256468ddfbd1`\n- `Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < 9c513dabd4540f811585a2087f23069767a284da`\n- `Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < 21a13f932972bc9836f58c44fcd47c62abdecd95`\n- `Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < ada4b9a5087ea7f30dd8e4c6411a4fb6547eb1ed`\n- `Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < 947b773caaa548672184df025271b29bdc80b0f1`\n- `Linux >= 9488585b21bef0df1217e510c7134905d1d376a7 < f20d61c22bcaf172d6790b6500e3838e532e71c8`\n- `Linux 5.0`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}