{"api_version":"1","generated_at":"2026-11-04T09:49:59+00:00","cve":"CVE-2026-87039","urls":{"html":"https://cve.report/CVE-2026-87039","api":"https://cve.report/api/cve/CVE-2026-87039.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-87039","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-87039"},"summary":{"title":"I2S configure syscall handler passes an unvalidated user-supplied kernel object pointer to drivers","description":"The user-mode syscall verifier z_vrfy_i2s_configure() in drivers/i2s/i2s_handlers.c copies the caller's struct i2s_config in from user memory and then, when cfg->frame_clk_freq is 0 (the API's \"unconfigure the stream\" request), jumps straight to z_impl_i2s_configure() without performing the K_SYSCALL_OBJ(config.mem_slab, K_OBJ_MEM_SLAB) ownership/type check or the block_size sanity check. The mem_slab field is a struct k_mem_slab *, so on that path a completely unvalidated, user-chosen pointer reaches driver code that is entitled to trust it as a real kernel object.\n\nAny thread running under CONFIG_USERSPACE that has access to an I2S device object can trigger this with a single i2s_configure() call. Most in-tree drivers special-case frame_clk_freq == 0 and never store the caller's structure, but drivers/i2s/i2s_litex.c does not: i2s_litex_configure() only logs a warning for a mismatched frame clock, then memcpy()s the caller's config into stream->cfg and marks the stream I2S_STATE_READY. A subsequent i2s_trigger() with I2S_TRIGGER_START enables the FIFO interrupt, and the interrupt handlers i2s_litex_isr_rx() / i2s_litex_isr_tx() then call k_mem_slab_alloc() and k_mem_slab_free() on the attacker-supplied pointer in supervisor context.\n\nThe result is an arbitrary-pointer read/write primitive executed by the kernel on behalf of an unprivileged thread — k_mem_slab_alloc() takes a spinlock at slab->lock and reads and writes slab->free_list and the link word inside the returned \"block\" — which defeats the CONFIG_USERSPACE isolation boundary entirely. The same missing validation is a hazard for out-of-tree I2S drivers that retain the configuration on the unconfigure path. Builds without CONFIG_USERSPACE are unaffected, since the verifier is not used.\n\nThe fix zeroes config.mem_slab and config.block_size on the unconfigure path so the driver can never receive an unvalidated pointer, while still allowing a stream to be unconfigured by a caller that does not own a memory slab, as the API documents.","state":"PUBLISHED","assigner":"zephyr","published_at":"2026-11-04 06:17:06","updated_at":"2026-11-04 06:17:06"},"problem_types":["CWE-787","CWE-787 memory-safety"],"metrics":[{"version":"3.1","source":"vulnerabilities@zephyrproject.org","type":"Secondary","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","data":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"}},{"version":"3.1","source":"CNA","type":"CVSS","score":"7.8","severity":"HIGH","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","data":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","version":"3.1"}}],"references":[{"url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-g43m-x6vj-5cg2","name":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-g43m-x6vj-5cg2","refsource":"vulnerabilities@zephyrproject.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://github.com/zephyrproject-rtos/zephyr/commit/e9898c4d22f69575d9b5f297b3df130ceaff1b8f","name":"https://github.com/zephyrproject-rtos/zephyr/commit/e9898c4d22f69575d9b5f297b3df130ceaff1b8f","refsource":"vulnerabilities@zephyrproject.org","tags":[],"title":"","mime":"","httpstatus":"","archivestatus":"0"},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-87039","name":"CVE Program record","refsource":"CVE.ORG","tags":["canonical"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-87039","name":"NVD vulnerability detail","refsource":"NVD","tags":["canonical","analysis"]}],"affected":[{"source":"CNA","vendor":"zephyrproject","product":"zephyr","version":"affected 4.4.0 4.5.0 semver","platforms":[]}],"timeline":[],"solutions":[],"workarounds":[],"exploits":[],"credits":[],"nvd_cpes":[],"vendor_comments":[],"enrichments":{"kev":null,"epss":null,"legacy_qids":[]},"source_records":{"cve_program":{"containers":{"cna":{"affected":[{"collectionURL":"https://github.com/zephyrproject-rtos/zephyr","defaultStatus":"unaffected","packageName":"zephyr","product":"zephyr","programFiles":["drivers/i2s/i2s_handlers.c","drivers/i2s/i2s_litex.c"],"programRoutines":[{"name":"i2s_litex_configure"},{"name":"i2s_litex_isr_rx"},{"name":"z_vrfy_i2s_configure"}],"vendor":"zephyrproject","versions":[{"lessThan":"4.5.0","status":"affected","version":"4.4.0","versionType":"semver"}]}],"descriptions":[{"lang":"en","value":"The user-mode syscall verifier z_vrfy_i2s_configure() in drivers/i2s/i2s_handlers.c copies the caller's struct i2s_config in from user memory and then, when cfg->frame_clk_freq is 0 (the API's \"unconfigure the stream\" request), jumps straight to z_impl_i2s_configure() without performing the K_SYSCALL_OBJ(config.mem_slab, K_OBJ_MEM_SLAB) ownership/type check or the block_size sanity check. The mem_slab field is a struct k_mem_slab *, so on that path a completely unvalidated, user-chosen pointer reaches driver code that is entitled to trust it as a real kernel object.\n\nAny thread running under CONFIG_USERSPACE that has access to an I2S device object can trigger this with a single i2s_configure() call. Most in-tree drivers special-case frame_clk_freq == 0 and never store the caller's structure, but drivers/i2s/i2s_litex.c does not: i2s_litex_configure() only logs a warning for a mismatched frame clock, then memcpy()s the caller's config into stream->cfg and marks the stream I2S_STATE_READY. A subsequent i2s_trigger() with I2S_TRIGGER_START enables the FIFO interrupt, and the interrupt handlers i2s_litex_isr_rx() / i2s_litex_isr_tx() then call k_mem_slab_alloc() and k_mem_slab_free() on the attacker-supplied pointer in supervisor context.\n\nThe result is an arbitrary-pointer read/write primitive executed by the kernel on behalf of an unprivileged thread — k_mem_slab_alloc() takes a spinlock at slab->lock and reads and writes slab->free_list and the link word inside the returned \"block\" — which defeats the CONFIG_USERSPACE isolation boundary entirely. The same missing validation is a hazard for out-of-tree I2S drivers that retain the configuration on the unconfigure path. Builds without CONFIG_USERSPACE are unaffected, since the verifier is not used.\n\nThe fix zeroes config.mem_slab and config.block_size on the unconfigure path so the driver can never receive an unvalidated pointer, while still allowing a stream to be unconfigured by a caller that does not own a memory slab, as the API documents."}],"metrics":[{"cvssV3_1":{"baseScore":7.8,"baseSeverity":"HIGH","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","version":"3.1"},"format":"CVSS"}],"problemTypes":[{"descriptions":[{"cweId":"CWE-787","description":"memory-safety","lang":"en","type":"CWE"}]}],"providerMetadata":{"dateUpdated":"2026-11-04T06:09:04.926Z","orgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","shortName":"zephyr"},"references":[{"name":"Fix commit","tags":["patch"],"url":"https://github.com/zephyrproject-rtos/zephyr/commit/e9898c4d22f69575d9b5f297b3df130ceaff1b8f"},{"name":"GHSA-g43m-x6vj-5cg2","url":"https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-g43m-x6vj-5cg2"}],"title":"I2S configure syscall handler passes an unvalidated user-supplied kernel object pointer to drivers","x_generator":{"engine":"cvelib 1.8.0"}}},"cveMetadata":{"assignerOrgId":"e2e69745-5e70-4e92-8431-deb5529a81ad","assignerShortName":"zephyr","cveId":"CVE-2026-87039","datePublished":"2026-11-04T06:09:04.926Z","dateReserved":"2026-09-08T18:40:40.197Z","dateUpdated":"2026-11-04T06:09:04.926Z","state":"PUBLISHED"},"dataType":"CVE_RECORD","dataVersion":"5.2"},"nvd":{"publishedDate":"2026-11-04 06:17:06","lastModifiedDate":"2026-11-04 06:17:06","problem_types":["CWE-787","CWE-787 memory-safety"],"metrics":{"cvssMetricV31":[{"source":"vulnerabilities@zephyrproject.org","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH","attackVector":"LOCAL","attackComplexity":"HIGH","privilegesRequired":"LOW","userInteraction":"NONE","scope":"CHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":1.1,"impactScore":6}]},"configurations":[]},"legacy_mitre":{"record":{"CveYear":"2026","CveId":"87039","Ordinal":"1","Title":"I2S configure syscall handler passes an unvalidated user-supplie","CVE":"CVE-2026-87039","Year":"2026"},"notes":[{"CveYear":"2026","CveId":"87039","Ordinal":"1","NoteData":"The user-mode syscall verifier z_vrfy_i2s_configure() in drivers/i2s/i2s_handlers.c copies the caller's struct i2s_config in from user memory and then, when cfg->frame_clk_freq is 0 (the API's \"unconfigure the stream\" request), jumps straight to z_impl_i2s_configure() without performing the K_SYSCALL_OBJ(config.mem_slab, K_OBJ_MEM_SLAB) ownership/type check or the block_size sanity check. The mem_slab field is a struct k_mem_slab *, so on that path a completely unvalidated, user-chosen pointer reaches driver code that is entitled to trust it as a real kernel object.\n\nAny thread running under CONFIG_USERSPACE that has access to an I2S device object can trigger this with a single i2s_configure() call. Most in-tree drivers special-case frame_clk_freq == 0 and never store the caller's structure, but drivers/i2s/i2s_litex.c does not: i2s_litex_configure() only logs a warning for a mismatched frame clock, then memcpy()s the caller's config into stream->cfg and marks the stream I2S_STATE_READY. A subsequent i2s_trigger() with I2S_TRIGGER_START enables the FIFO interrupt, and the interrupt handlers i2s_litex_isr_rx() / i2s_litex_isr_tx() then call k_mem_slab_alloc() and k_mem_slab_free() on the attacker-supplied pointer in supervisor context.\n\nThe result is an arbitrary-pointer read/write primitive executed by the kernel on behalf of an unprivileged thread — k_mem_slab_alloc() takes a spinlock at slab->lock and reads and writes slab->free_list and the link word inside the returned \"block\" — which defeats the CONFIG_USERSPACE isolation boundary entirely. The same missing validation is a hazard for out-of-tree I2S drivers that retain the configuration on the unconfigure path. Builds without CONFIG_USERSPACE are unaffected, since the verifier is not used.\n\nThe fix zeroes config.mem_slab and config.block_size on the unconfigure path so the driver can never receive an unvalidated pointer, while still allowing a stream to be unconfigured by a caller that does not own a memory slab, as the API documents.","Type":"Description","Title":"I2S configure syscall handler passes an unvalidated user-supplie"}]}}}