CVE-2026-90833 (GCVE-0-2026-90833)
Vulnerability from cvelistv5 – Published: 2026-11-10 22:07 – Updated: 2026-11-10 22:07
VLAI
EPSS
VEX
Title
Signed offset bypasses bounds check in simulated EEPROM driver, allowing out-of-bounds kernel memory read and write from user mode
Summary
The simulated EEPROM driver validated access ranges in eeprom_range_is_valid() (drivers/eeprom/eeprom_simulator.c) with a single test, (offset + len) <= config->size. Because offset is a signed off_t and len an unsigned size_t of the same rank, the addition is evaluated in unsigned arithmetic: a negative offset combined with a compensating len wraps the sum back into the accepted range. eeprom_sim_read() and eeprom_sim_write() then memcpy() through the EEPROM(addr) macro, which is plain pointer arithmetic on the driver's static mock_eeprom array, so the copy addresses memory located before that array.
eeprom_read() and eeprom_write() are __syscall entry points, and their verification handlers in drivers/eeprom/eeprom_handlers.c check only the device object and the caller's own data buffer (K_SYSCALL_MEMORY_READ/K_SYSCALL_MEMORY_WRITE) — the offset argument is passed to the driver unvalidated. With CONFIG_USERSPACE=y, a CONFIG_EEPROM_SIMULATOR device instance, and the device object granted to a user thread (the usage the in-tree tests/drivers/eeprom/api suite exercises from ZTEST_USER threads), an unprivileged thread could supply a negative offset and have the kernel perform the copy on its behalf.
The result is an out-of-bounds read of kernel .bss returned into the caller's buffer and, via the write path, an out-of-bounds write of caller-supplied bytes over kernel memory preceding mock_eeprom. Both the start address and the length of the affected span are attacker-selected, so the primitive is sufficient to corrupt adjacent kernel state and escape the user-mode sandbox. Exposure is limited to builds that instantiate the simulated EEPROM (status = "okay" by default on qemu_x86 and native_sim, otherwise added by a devicetree overlay) together with userspace isolation.
The fix rejects negative offsets and performs the remaining bound check without overflow.
Severity
7.8 (High)
CWE
- CWE-787 - bounds
Assigner
References
2 references
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| zephyrproject | zephyr |
Affected:
2.2.0 , < 4.3.2
(semver)
Affected: 4.4.0 , < 4.5.0 (semver) |
guessed |
{
"containers": {
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{
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"defaultStatus": "unaffected",
"packageName": "zephyr",
"product": "zephyr",
"programFiles": [
"drivers/eeprom/eeprom_simulator.c"
],
"programRoutines": [
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"name": "eeprom_range_is_valid"
},
{
"name": "eeprom_sim_read"
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{
"name": "eeprom_sim_write"
},
{
"name": "z_vrfy_eeprom_read"
},
{
"name": "z_vrfy_eeprom_write"
}
],
"vendor": "zephyrproject",
"versions": [
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"status": "affected",
"version": "2.2.0",
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{
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"version": "4.4.0",
"versionType": "semver"
}
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"descriptions": [
{
"lang": "en",
"value": "The simulated EEPROM driver validated access ranges in eeprom_range_is_valid() (drivers/eeprom/eeprom_simulator.c) with a single test, (offset + len) \u003c= config-\u003esize. Because offset is a signed off_t and len an unsigned size_t of the same rank, the addition is evaluated in unsigned arithmetic: a negative offset combined with a compensating len wraps the sum back into the accepted range. eeprom_sim_read() and eeprom_sim_write() then memcpy() through the EEPROM(addr) macro, which is plain pointer arithmetic on the driver\u0027s static mock_eeprom array, so the copy addresses memory located before that array.\n\neeprom_read() and eeprom_write() are __syscall entry points, and their verification handlers in drivers/eeprom/eeprom_handlers.c check only the device object and the caller\u0027s own data buffer (K_SYSCALL_MEMORY_READ/K_SYSCALL_MEMORY_WRITE) \u2014 the offset argument is passed to the driver unvalidated. With CONFIG_USERSPACE=y, a CONFIG_EEPROM_SIMULATOR device instance, and the device object granted to a user thread (the usage the in-tree tests/drivers/eeprom/api suite exercises from ZTEST_USER threads), an unprivileged thread could supply a negative offset and have the kernel perform the copy on its behalf.\n\nThe result is an out-of-bounds read of kernel .bss returned into the caller\u0027s buffer and, via the write path, an out-of-bounds write of caller-supplied bytes over kernel memory preceding mock_eeprom. Both the start address and the length of the affected span are attacker-selected, so the primitive is sufficient to corrupt adjacent kernel state and escape the user-mode sandbox. Exposure is limited to builds that instantiate the simulated EEPROM (status = \"okay\" by default on qemu_x86 and native_sim, otherwise added by a devicetree overlay) together with userspace isolation.\n\nThe fix rejects negative offsets and performs the remaining bound check without overflow."
}
],
"metrics": [
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"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
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}
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"descriptions": [
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"cweId": "CWE-787",
"description": "bounds",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-11-10T22:07:42.603Z",
"orgId": "e2e69745-5e70-4e92-8431-deb5529a81ad",
"shortName": "zephyr"
},
"references": [
{
"name": "Fix commit",
"tags": [
"patch"
],
"url": "https://github.com/zephyrproject-rtos/zephyr/commit/ce2ec9b3a34d71f52f5d1d7491b91393e334713e"
},
{
"name": "GHSA-vf6j-hcx8-44vh",
"url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-vf6j-hcx8-44vh"
}
],
"title": "Signed offset bypasses bounds check in simulated EEPROM driver, allowing out-of-bounds kernel memory read and write from user mode",
"x_generator": {
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"cveMetadata": {
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"assignerShortName": "zephyr",
"cveId": "CVE-2026-90833",
"datePublished": "2026-11-10T22:07:42.603Z",
"dateReserved": "2026-09-13T19:22:58.656Z",
"dateUpdated": "2026-11-10T22:07:42.603Z",
"state": "PUBLISHED"
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"defaultStatus": "unaffected",
"packageName": "zephyr",
"product": "zephyr",
"programFiles": [
"drivers/eeprom/eeprom_simulator.c"
],
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"name": "eeprom_range_is_valid"
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{
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{
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{
"name": "z_vrfy_eeprom_read"
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{
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"vendor": "zephyrproject",
"versions": [
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"status": "affected",
"version": "2.2.0",
"versionType": "semver"
},
{
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"status": "affected",
"version": "4.4.0",
"versionType": "semver"
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]
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],
"source": "vulnerabilities@zephyrproject.org"
}
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"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "The simulated EEPROM driver validated access ranges in eeprom_range_is_valid() (drivers/eeprom/eeprom_simulator.c) with a single test, (offset + len) \u003c= config-\u003esize. Because offset is a signed off_t and len an unsigned size_t of the same rank, the addition is evaluated in unsigned arithmetic: a negative offset combined with a compensating len wraps the sum back into the accepted range. eeprom_sim_read() and eeprom_sim_write() then memcpy() through the EEPROM(addr) macro, which is plain pointer arithmetic on the driver\u0027s static mock_eeprom array, so the copy addresses memory located before that array.\n\neeprom_read() and eeprom_write() are __syscall entry points, and their verification handlers in drivers/eeprom/eeprom_handlers.c check only the device object and the caller\u0027s own data buffer (K_SYSCALL_MEMORY_READ/K_SYSCALL_MEMORY_WRITE) \u2014 the offset argument is passed to the driver unvalidated. With CONFIG_USERSPACE=y, a CONFIG_EEPROM_SIMULATOR device instance, and the device object granted to a user thread (the usage the in-tree tests/drivers/eeprom/api suite exercises from ZTEST_USER threads), an unprivileged thread could supply a negative offset and have the kernel perform the copy on its behalf.\n\nThe result is an out-of-bounds read of kernel .bss returned into the caller\u0027s buffer and, via the write path, an out-of-bounds write of caller-supplied bytes over kernel memory preceding mock_eeprom. Both the start address and the length of the affected span are attacker-selected, so the primitive is sufficient to corrupt adjacent kernel state and escape the user-mode sandbox. Exposure is limited to builds that instantiate the simulated EEPROM (status = \"okay\" by default on qemu_x86 and native_sim, otherwise added by a devicetree overlay) together with userspace isolation.\n\nThe fix rejects negative offsets and performs the remaining bound check without overflow."
}
],
"id": "CVE-2026-90833",
"lastModified": "2026-11-10T22:21:14.427",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.8,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 5.9,
"source": "vulnerabilities@zephyrproject.org",
"type": "Secondary"
}
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},
"published": "2026-11-10T22:21:14.320",
"references": [
{
"source": "vulnerabilities@zephyrproject.org",
"url": "https://github.com/zephyrproject-rtos/zephyr/commit/ce2ec9b3a34d71f52f5d1d7491b91393e334713e"
},
{
"source": "vulnerabilities@zephyrproject.org",
"url": "https://github.com/zephyrproject-rtos/zephyr/security/advisories/GHSA-vf6j-hcx8-44vh"
}
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"sourceIdentifier": "vulnerabilities@zephyrproject.org",
"vulnStatus": "Awaiting Analysis",
"weaknesses": [
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"description": [
{
"lang": "en",
"value": "CWE-787"
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"source": "vulnerabilities@zephyrproject.org",
"type": "Secondary"
}
]
}
}
}
}
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