{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-87039", "assignerOrgId": "e2e69745-5e70-4e92-8431-deb5529a81ad", "state": "PUBLISHED", "assignerShortName": "zephyr", "dateReserved": "2026-09-08T18:40:40.197Z", "datePublished": "2026-11-04T06:09:04.926Z", "dateUpdated": "2026-11-04T06:09:04.926Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "e2e69745-5e70-4e92-8431-deb5529a81ad", "shortName": "zephyr", "dateUpdated": "2026-11-04T06:09:04.926Z"}, "title": "I2S configure syscall handler passes an unvalidated user-supplied kernel object pointer to drivers", "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 \u2014 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\" \u2014 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."}], "affected": [{"vendor": "zephyrproject", "product": "zephyr", "collectionURL": "https://github.com/zephyrproject-rtos/zephyr", "packageName": "zephyr", "defaultStatus": "unaffected", "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"}], "versions": [{"version": "4.4.0", "status": "affected", "versionType": "semver", "lessThan": "4.5.0"}]}], "references": [{"url": "https://github.com/zephyrproject-rtos/zephyr/commit/e9898c4d22f69575d9b5f297b3df130ceaff1b8f", "name": "Fix commit", "tags": ["patch"]}, {"url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-g43m-x6vj-5cg2", "name": "GHSA-g43m-x6vj-5cg2"}], "metrics": [{"format": "CVSS", "cvssV3_1": {"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"}}], "problemTypes": [{"descriptions": [{"lang": "en", "description": "memory-safety", "cweId": "CWE-787", "type": "CWE"}]}], "x_generator": {"engine": "cvelib 1.8.0"}}}}

{}

{"affected": [{"affectedData": [{"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"}]}], "source": "vulnerabilities@zephyrproject.org"}], "cveTags": [], "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 \u2014 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\" \u2014 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."}], "id": "CVE-2026-87039", "lastModified": "2026-11-04T06:17:06.733", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "HIGH", "attackVector": "LOCAL", "availabilityImpact": "HIGH", "baseScore": 7.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 1.1, "impactScore": 6.0, "source": "vulnerabilities@zephyrproject.org", "type": "Secondary"}]}, "published": "2026-11-04T06:17:06.623", "references": [{"source": "vulnerabilities@zephyrproject.org", "url": "https://github.com/zephyrproject-rtos/zephyr/commit/e9898c4d22f69575d9b5f297b3df130ceaff1b8f"}, {"source": "vulnerabilities@zephyrproject.org", "url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-g43m-x6vj-5cg2"}], "sourceIdentifier": "vulnerabilities@zephyrproject.org", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-787"}], "source": "vulnerabilities@zephyrproject.org", "type": "Secondary"}]}

{}

{}