CVE-2023-33613

Vulnerability

axTLS v2.1.5 is affected by a heap buffer overflow vulnerability in the bi_import function in axtls-code/crypto/bigint.c. The bug occurs when parsing a specially crafted private key, causing a read access beyond the allocated heap buffer. This issue exists in the latest release v2.1.5 [1].

Exploitation

An attacker can trigger the vulnerability by supplying a malicious private key file to an axTLS server (e.g., via the -key option). The server will parse the key, leading to a heap buffer overflow. No authentication is required if the attacker can control the private key input [1].

Impact

Successful exploitation causes a heap buffer overflow, resulting in a denial of service (DoS) due to application crash. The overflow is a read of size 1 beyond the buffer, as detected by AddressSanitizer, and may also lead to unpredictable behavior [1].

Mitigation

No official patch or fixed version has been released for axTLS v2.1.5 as of the publication date. Users should limit exposure by avoiding the use of untrusted private keys or switching to an alternative TLS library until a fix is available [1].