Out-of-bounds memory access via allocation overflow
Published May 3, 2022 · Updated Apr 16, 2025
Integer overflow in Arm Mbed OS 6.0 through 6.8 and 5.15.6 and earlier allows attackers to access memory outside an allocation. When heap statistics are enabled, malloc_wrapper adds sizeof(alloc_info_t) to an untrusted size without checking size_t overflow, then returns an undersized buffer as successful. Exploitation requires heap statistics and a caller that permits one allocation near SIZE_MAX; subsequent use can expose memory, crash the device, or enable code execution.
Summary
What happened
Integer overflow in Arm Mbed OS 6.0 through 6.8 and 5.15.6 and earlier allows attackers to access memory outside an allocation. When heap statistics are enabled, malloc_wrapper adds sizeof(alloc_info_t) to an untrusted size without checking size_t overflow, then returns an undersized buffer as successful. Exploitation requires heap statistics and a caller that permits one allocation near SIZE_MAX; subsequent use can expose memory, crash the device, or enable code execution.
The record
- CVE
- CVE-2021-27435
- Published
- May 3, 2022
- Updated
- Apr 16, 2025
- Vendor
- Arm
- Product
- Arm Mbed OS
- Classifications
- CWE-190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 3, 2022CVE publishedPublication date reported by the CVE source.
- Apr 16, 2025Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=6.3.0
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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