What is the CVSS score of CVE-2021-47640?

CVE-2021-47640 has a CVSS 3.1 base score of 7.8 (High). CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Which versions of Linux Kernel are affected by CVE-2021-47640?

CVE-2021-47640 presents notable security risk, a out-of-bounds write vulnerability rated CVSS 7.8.. A patch is available.

How to fix or mitigate CVE-2021-47640?

Within 7 days: Identify all affected systems and apply vendor patches promptly. If patching is delayed, consider network segmentation to limit exposure.

Linux Kernel CVE-2021-47640

HIGH

Out-of-bounds Write (CWE-787)

2025-02-26 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Memory Corruption Buffer Overflow Linux Linux Kernel Red Hat Suse

7.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

7.8 HIGH

AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

SUSE

HIGH

qualitative

Red Hat

7.8 HIGH

qualitative

Primary rating from NVD.

CVSS VectorNVD

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 18:28 vuln.today

Patch released

Mar 28, 2026 - 18:28 nvd

Patch available

CVE Published

Feb 26, 2025 - 06:37 nvd

HIGH 7.8

DescriptionCVE.org

In the Linux kernel, the following vulnerability has been resolved:

powerpc/kasan: Fix early region not updated correctly

The shadow's page table is not updated when PTE_RPN_SHIFT is 24 and PAGE_SHIFT is 12. It not only causes false positives but also false negative as shown the following text.

Fix it by bringing the logic of kasan_early_shadow_page_entry here.

False Positive:

============== BUG: KASAN: vmalloc-out-of-bounds in pcpu_alloc+0x508/0xa50 Write of size 16 at addr f57f3be0 by task swapper/0/1

CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-12267-gdebe436e77c7 #1 Call Trace: [c80d1c20] [c07fe7b8] dump_stack_lvl+0x4c/0x6c (unreliable) [c80d1c40] [c02ff668] print_address_description.constprop.0+0x88/0x300 [c80d1c70] [c02ff45c] kasan_report+0x1ec/0x200 [c80d1cb0] [c0300b20] kasan_check_range+0x160/0x2f0 [c80d1cc0] [c03018a4] memset+0x34/0x90 [c80d1ce0] [c0280108] pcpu_alloc+0x508/0xa50 [c80d1d40] [c02fd7bc] __kmem_cache_create+0xfc/0x570 [c80d1d70] [c0283d64] kmem_cache_create_usercopy+0x274/0x3e0 [c80d1db0] [c2036580] init_sd+0xc4/0x1d0 [c80d1de0] [c00044a0] do_one_initcall+0xc0/0x33c [c80d1eb0] [c2001624] kernel_init_freeable+0x2c8/0x384 [c80d1ef0] [c0004b14] kernel_init+0x24/0x170 [c80d1f10] [c001b26c] ret_from_kernel_thread+0x5c/0x64

Memory state around the buggy address: f57f3a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f57f3b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >f57f3b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ f57f3c00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f57f3c80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ==============

False Negative (with KASAN tests):

============== Before fix: ok 45 - kmalloc_double_kzfree

vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039

KASAN failure expected in "((volatile char *)area)[3100]", but none occurred not ok 46 - vmalloc_oob not ok 1 - kasan

============== After fix: ok 1 - kasan

AnalysisAI

In the Linux kernel, the following vulnerability has been resolved: powerpc/kasan: Fix early region not updated correctly The shadow's page table is not updated when PTE_RPN_SHIFT is 24 and. Rated high severity (CVSS 7.8), this vulnerability is low attack complexity. This Out-of-bounds Write vulnerability could allow attackers to write data beyond allocated buffer boundaries leading to code execution or crashes.

Technical ContextAI

This vulnerability is classified as Out-of-bounds Write (CWE-787), which allows attackers to write data beyond allocated buffer boundaries leading to code execution or crashes. In the Linux kernel, the following vulnerability has been resolved: powerpc/kasan: Fix early region not updated correctly The shadow's page table is not updated when PTE_RPN_SHIFT is 24 and PAGE_SHIFT is 12. It not only causes false positives but also false negative as shown the following text. Fix it by bringing the logic of kasan_early_shadow_page_entry here. 1. False Positive: ============== BUG: KASAN: vmalloc-out-of-bounds in pcpu_alloc+0x508/0xa50 Write of size 16 at addr f57f3be0 by task swapper/0/1 CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-12267-gdebe436e77c7 #1 Call Trace: [c80d1c20] [c07fe7b8] dump_stack_lvl+0x4c/0x6c (unreliable) [c80d1c40] [c02ff668] print_address_description.constprop.0+0x88/0x300 [c80d1c70] [c02ff45c] kasan_report+0x1ec/0x200 [c80d1cb0] [c0300b20] kasan_check_range+0x160/0x2f0 [c80d1cc0] [c03018a4] memset+0x34/0x90 [c80d1ce0] [c0280108] pcpu_alloc+0x508/0xa50 [c80d1d40] [c02fd7bc] __kmem_cache_create+0xfc/0x570 [c80d1d70] [c0283d64] kmem_cache_create_usercopy+0x274/0x3e0 [c80d1db0] [c2036580] init_sd+0xc4/0x1d0 [c80d1de0] [c00044a0] do_one_initcall+0xc0/0x33c [c80d1eb0] [c2001624] kernel_init_freeable+0x2c8/0x384 [c80d1ef0] [c0004b14] kernel_init+0x24/0x170 [c80d1f10] [c001b26c] ret_from_kernel_thread+0x5c/0x64 Memory state around the buggy address: f57f3a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f57f3b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 >f57f3b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ^ f57f3c00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f57f3c80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 ============== 2. False Negative (with KASAN tests): ============== Before fix: ok 45 - kmalloc_double_kzfree

vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039 KASAN failure expected in "((volatile char *)area)[3100]", but none occurred not ok 46 - vmalloc_oob not ok 1 - kasan ============== After fix: ok 1 - kasan Affected products include: Linux Linux Kernel.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Validate write boundaries, use memory-safe languages, enable compiler protections (ASLR, stack canaries).

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Vendor StatusVendor

SUSE

Severity: High

Product	Status
SUSE Linux Enterprise Micro 5.2	Fixed
SUSE Linux Enterprise Micro 5.2	Fixed
SUSE Linux Enterprise Micro 5.2	Fixed
SUSE Linux Enterprise Micro 5.2	Fixed
SUSE Linux Enterprise Micro 5.3	Fixed

CVE-2021-47640 vulnerability details – vuln.today

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Linux Kernel CVE-2021-47640

Severity by source

CVSS VectorNVD

Lifecycle Timeline

DescriptionCVE.org

vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039

AnalysisAI

Technical ContextAI

vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039 KASAN failure expected in "((volatile char *)area)[3100]", but none occurred not ok 46 - vmalloc_oob not ok 1 - kasan ============== After fix: ok 1 - kasan Affected products include: Linux Linux Kernel.

RemediationAI

More in Linux Kernel

Same weakness CWE-787 – Out-of-bounds Write

Same technique Memory Corruption

Vendor StatusVendor

SUSE

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External POC / Exploit Code