Executive Summary

[{'type': 'paragraph', 'content': "This vulnerability is a heap-based buffer overflow in the wolfSSL library's KCAPI ECC code path, specifically in the function wc_ecc_import_x963_ex(). It occurs because the function copies an EC public key point into a fixed-size buffer (pubkey_raw) without checking if the input size exceeds the buffer's capacity. A remote attacker can exploit this by sending a crafted oversized EC public key during a TLS key exchange, causing data to be written beyond the buffer's bounds."}, {'type': 'paragraph', 'content': 'The issue arises because the WOLFSSL_KCAPI_ECC code path uses XMEMCPY to copy the input directly without validating its length, unlike other code paths that perform length checks. This can lead to memory corruption or security issues.'}, {'type': 'paragraph', 'content': 'The vulnerability was fixed by adding a length check before copying the public key data, ensuring that if the input is larger than the buffer, the function returns an error instead of copying the data.'}] [1]

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Impact Analysis

[{'type': 'paragraph', 'content': 'This vulnerability can allow a remote attacker to cause a buffer overflow by sending a specially crafted EC public key during a TLS key exchange. The overflow can lead to memory corruption, which might be exploited to crash the application, cause denial of service, or potentially execute arbitrary code.'}, {'type': 'paragraph', 'content': "Because the vulnerability occurs during TLS key exchange, it affects the security and stability of encrypted communications that rely on wolfSSL's ECC implementation under the KCAPI configuration."}] [1]

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': "This vulnerability occurs during the TLS key exchange when a malicious peer sends a crafted ECPoint in ServerKeyExchange that triggers a heap-based buffer overflow in the wolfSSL library's ECC key import function. Detection involves monitoring TLS handshake messages for unusually large or malformed EC public key points."}, {'type': 'paragraph', 'content': 'Since the vulnerability is triggered by a crafted oversized EC public key point, network detection could involve inspecting TLS ServerKeyExchange messages for ECPoints exceeding expected sizes.'}, {'type': 'paragraph', 'content': 'However, no specific detection commands or tools are provided in the available resources.'}] [1]

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Mitigation Strategies

The immediate mitigation step is to update the wolfSSL library to version 5.9.0 or later, which includes the fix for this vulnerability.

The fix introduces a length check before copying the EC public key data, preventing buffer overflow by returning an error if the input exceeds the buffer size.

Until the update is applied, consider restricting or monitoring TLS connections that use the WOLFSSL_KCAPI_ECC configuration to reduce exposure.

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