{"id":"CVE-2026-28386","title":"Issue summary: Applications using AES-CFB128 encryption or decryption on\nsystems with AVX-512 and VAES support can trigger an out-of-bounds read\nof up to 15 bytes when processing partial cipher blocks.\n\nImpact summary: This out-of-bounds…","summary":"Issue summary: Applications using AES-CFB128 encryption or decryption on\nsystems with AVX-512 and VAES support can trigger an out-of-bounds read\nof up to 15 bytes when processing partial cipher blocks.\n\nImpact summary: This out-of-bounds…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cwe":["CWE-125"],"vendor":"openssl","product":"openssl","affected":["openssl >= 3.6.0, < 3.6.2"],"patched":["openssl 3.6.2"],"published":"2026-04-07","updated":"2026-07-24","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-28386","references":[{"url":"https://github.com/openssl/openssl/commit/61f428a2fc6671ede184a19f71e6e495f0689621","label":"openssl-security@openssl.org"},{"url":"https://openssl-library.org/news/secadv/20260407.txt","label":"openssl-security@openssl.org"}],"tags":["nvd"],"epss":0.00313,"epssPercentile":0.24459,"ingestedAt":"2026-07-25T23:05:58.078Z","slug":"CVE-2026-28386","body":"## Overview\n\nIssue summary: Applications using AES-CFB128 encryption or decryption on\nsystems with AVX-512 and VAES support can trigger an out-of-bounds read\nof up to 15 bytes when processing partial cipher blocks.\n\nImpact summary: This out-of-bounds read may trigger a crash which leads to\nDenial of Service for an application if the input buffer ends at a memory\npage boundary and the following page is unmapped. There is no information\ndisclosure as the over-read bytes are not written to output.\n\nThe vulnerable code path is only reached when processing partial blocks\n(when a previous call left an incomplete block and the current call provides\nfewer bytes than needed to complete it). Additionally, the input buffer\nmust be positioned at a page boundary with the following page unmapped.\nCFB mode is not used in TLS/DTLS protocols, which use CBC, GCM, CCM, or\nChaCha20-Poly1305 instead. For these reasons the issue was assessed as\nLow severity according to our Security Policy.\n\nOnly x86-64 systems with AVX-512 and VAES instruction support are affected.\nOther architectures and systems without VAES support use different code\npaths that are not affected.\n\nOpenSSL FIPS module in 3.6 version is affected by this issue.\n\n## Affected\n\n- `openssl >= 3.6.0, < 3.6.2`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `openssl 3.6.2`","depth":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}