Out-of-bounds Read in OpenSSL AES-CFB-128 on x86-64 with AVX-512/VAES support
CVE-2026-28386 is an out-of-bounds read in OpenSSL’s AES-CFB128 encryption/decryption implementation on x86-64 systems that use the AVX-512/VAES optimized code path. When processing partial cipher blocks, specifically when a previous call left an incomplete block and a subsequent call supplies fewer bytes than needed to complete it, the affected implementation can read up to 15 bytes past the end of the input buffer. The issue is limited to the AVX-512/VAES path on x86-64; other architectures and systems without VAES support use different code paths and are not affected. The over-read bytes are not written to output. The OpenSSL 3.6 branch is affected, and the OpenSSL FIPS module in version 3.6 is also affected.
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Impact, mitigation & remediation
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Impact
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Mitigation
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Remediation
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Exploits
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No public exploit code observed for this vulnerability.
Affected products & vendors
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Recent activity
9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
An out-of-bounds read in AES-CFB-128 affecting x86-64 CPUs with AVX-512 support in OpenSSL.
An out-of-bounds read in the AES-CFB-128 AVX-512 implementation on x86-64 systems, leading to memory-read exposure and potential information disclosure.
Out-of-bounds read in AES-CFB-128 on x86-64 systems with AVX-512 support in OpenSSL.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.