{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-72151", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.908Z", "datePublished": "2026-08-15T05:53:22.196Z", "dateUpdated": "2026-08-17T05:41:00.459Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:41:00.459Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntpm: tpm2-sessions: wait for async KPP completion in tpm_buf_append_salt\n\ntpm_buf_append_salt() in drivers/char/tpm/tpm2-sessions.c calls\ncrypto_kpp_generate_public_key() and crypto_kpp_compute_shared_secret()\nwithout installing a completion callback, discards both return values,\nand immediately frees the kpp_request via kpp_request_free(). When the\nresolved ecdh-nist-p256 KPP backend is asynchronous (atmel-ecc, HPRE,\nkeembay-ocs), either operation returns -EINPROGRESS and the deferred\ncompletion worker dereferences the freed request.\n\nThe path fires automatically from the hwrng_fillfn kernel thread via\ntpm_get_random -> tpm2_get_random -> tpm2_start_auth_session ->\ntpm_buf_append_salt on every entropy poll, without any userland action.\n\nInstall crypto_req_done as the completion callback, wrap both KPP\noperations in crypto_wait_req(), and propagate errors to the caller.\nThe wait is a no-op for synchronous backends." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 8.4, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerable code is reached only via local kernel TPM/HWRNG paths (hwrng_fillfn kernel thread polling tpm_get_random, or local /dev/hwrng reads); there is no network, adjacent-radio, or physical-access entry point to tpm_buf_append_salt.\nAC:L - On affected builds (CONFIG_TCG_TPM2_HMAC plus an async ecdh-nist-p256 backend), the UAF is deterministically triggered each auth-session setup without winning a race; async KPP returns -EINPROGRESS and the completion worker later dereferences the already-freed kpp_request.\nPR:N - No attacker credentials are required: the hwrng kernel thread invokes tpm2_start_auth_session automatically on TPM RNG polls, and unprivileged local processes can also reach tpm_get_random via /dev/hwrng without root or namespaced admin capabilities.\nUI:N - Exploitation does not require any victim user action such as mounting a filesystem or opening a file; the bug fires from background kernel entropy collection and TPM session setup without interactive steps.\nS:U - Impact is confined to kernel memory integrity and availability on the same host; it is a standard kernel heap UAF, not a cross-boundary escape such as guest-to-host VM breakout or IOMMU/DMA bypass.\nC:H - Use-after-free of a kmalloc'd kpp_request lets an attacker influence freed heap contents and potentially obtain arbitrary kernel memory read primitives through heap grooming, not merely a bounded leak.\nI:H - The UAF corrupts kernel heap metadata/object lifetimes and can be leveraged for arbitrary write or control-flow hijack (privilege escalation), not just limited or transient data modification.\nA:H - The deferred crypto completion dereferences freed memory, causing kernel oops/panic or hang during normal TPM RNG polling, yielding complete loss of system availability on affected hardware." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/char/tpm/tpm2-sessions.c" ], "versions": [ { "version": "1085b8276bb4239daa7008f0dcd5c973e4bd690f", "lessThan": "111e520efbe82b324bc42b1999b723c0619eea6d", "status": "affected", "versionType": "git" }, { "version": "1085b8276bb4239daa7008f0dcd5c973e4bd690f", "lessThan": "934d1cd40e2893bf7a041b54f6afd1c008d7a21c", "status": "affected", "versionType": "git" }, { "version": "1085b8276bb4239daa7008f0dcd5c973e4bd690f", "lessThan": "493333f167926c7adab8e7563e21ad71d8af84fa", "status": "affected", "versionType": "git" }, { "version": "1085b8276bb4239daa7008f0dcd5c973e4bd690f", "lessThan": "73851a7c43dfa52d2ed9415889b33daf85da0ed9", "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/tpm2-sessions.c" ], "versions": [ { "version": "6.10", "status": "affected" }, { "version": "0", "lessThan": "6.10", "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": "6.10", "versionEndExcluding": "6.12.97" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "6.18.40" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "7.1.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.10", "versionEndExcluding": "7.2" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/111e520efbe82b324bc42b1999b723c0619eea6d" }, { "url": "https://git.kernel.org/stable/c/934d1cd40e2893bf7a041b54f6afd1c008d7a21c" }, { "url": "https://git.kernel.org/stable/c/493333f167926c7adab8e7563e21ad71d8af84fa" }, { "url": "https://git.kernel.org/stable/c/73851a7c43dfa52d2ed9415889b33daf85da0ed9" } ], "title": "tpm: tpm2-sessions: wait for async KPP completion in tpm_buf_append_salt", "x_generator": { "engine": "bippy-1.2.0" } } } }