Platform
openssl
Component
openssl
Fixed in
3.6.2
CVE-2026-28386 describes an out-of-bounds read vulnerability discovered in OpenSSL. This flaw occurs when applications utilizing AES-CFB128 encryption or decryption on systems equipped with AVX-512 and VAES support process partial cipher blocks, potentially leading to a Denial of Service crash. The vulnerability impacts OpenSSL versions 3.6.0 through 3.6.2, and a fix is available in version 3.6.2.
CVE-2026-28386 in OpenSSL affects applications using AES-CFB128 encryption or decryption on systems with AVX-512 and VAES support. An out-of-bounds read of up to 15 bytes can be triggered when processing partial cipher blocks. While there's no information disclosure as the over-read bytes aren't written to output, this vulnerability can lead to an application crash under specific conditions. The risk is heightened if the input buffer ends at a memory page boundary and the subsequent page is unmapped, potentially resulting in a Denial of Service (DoS). The severity depends on the likelihood of these conditions and the impact on service availability.
Exploitation of CVE-2026-28386 requires specific conditions: AES-CFB128 usage, the presence of AVX-512 and VAES, and the input buffer ending at a memory page boundary with an unmapped subsequent page. This makes exploitation less likely than with more general vulnerabilities, but it still poses a potential risk. Attackers might attempt to manipulate input to force the alignment condition and trigger an application crash. The complexity of exploitation limits its scope, but doesn't eliminate the need for the fix.
Exploit Status
EPSS
0.07% (21% percentile)
The solution to mitigate CVE-2026-28386 is to upgrade to OpenSSL version 3.6.2 or later. This version includes a fix that prevents the out-of-bounds read. Applying this update promptly, especially in critical environments, is highly recommended. Reviewing OpenSSL security configurations and dependencies to ensure updated versions and best security practices are implemented is also advised. Continuous system monitoring for potential exploits is an important preventative measure.
Actualice a OpenSSL versión 3.6.2 o superior para mitigar la vulnerabilidad. Esta actualización corrige un error de lectura fuera de límites en el modo AES-CFB-128 que puede causar una denegación de servicio en sistemas x86-64 con AVX-512 y VAES.
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AES-CFB128 is a mode of operation for the AES block cipher using a 128-bit block. It's a block cipher mode used to protect sensitive data.
AVX-512 is a set of instruction set extensions for x86 processors that allows vectorized operations on 512-bit data. VAES is an AVX-512 extension providing accelerated instructions for AES encryption.
Verify the OpenSSL version installed on your system. If you're using a version prior to 3.6.2, you are vulnerable. You can use the command openssl version in the command line.
Temporary workarounds are not recommended. Upgrading to the patched version is the best option. Avoiding AES-CFB128 usage on vulnerable systems could be an option, but might affect application functionality.
If you cannot update immediately, monitor your systems for suspicious activity and consider implementing additional security measures, such as firewalls and intrusion detection systems.
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