{"id":"CVE-2023-40547","title":"A remote code execution vulnerability was found in Shim","summary":"A remote code execution vulnerability was found in Shim. The Shim boot support trusts attacker-controlled values when parsing an HTTP response. This flaw allows an attacker to craft a specific malicious HTTP request, leading to a complet…","severity":"high","cvss":8.3,"cvssVector":"CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H","cwe":["CWE-787","CWE-346","CWE-787"],"vendor":"redhat","product":"shim","affected":["shim < 15.8","enterprise_linux = 7.0","enterprise_linux = 8.0","enterprise_linux = 9.0"],"patched":["shim 15.8"],"published":"2024-01-25","updated":"2026-06-26","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2023-40547","references":[{"url":"https://access.redhat.com/errata/RHSA-2024:1834","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2024:1835","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2024:1873","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2024:1876","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2024:1883","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2024:1902","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2024:1903","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2024:1959","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/errata/RHSA-2024:2086","label":"secalert@redhat.com"},{"url":"https://access.redhat.com/security/cve/CVE-2023-40547","label":"secalert@redhat.com"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2234589","label":"secalert@redhat.com"},{"url":"http://www.openwall.com/lists/oss-security/2024/01/26/1","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2024:1834","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2024:1835","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2024:1873","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2024:1876","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2024:1883","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2024:1902","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2024:1903","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2024:1959","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/errata/RHSA-2024:2086","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://access.redhat.com/security/cve/CVE-2023-40547","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2234589","label":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2024/05/msg00009.html","label":"af854a3a-2127-422b-91ae-364da2661108"}],"tags":["nvd"],"epss":0.05417,"epssPercentile":0.92396,"ingestedAt":"2026-06-26T16:43:13.375Z","slug":"CVE-2023-40547","body":"## Overview\n\nA remote code execution vulnerability was found in Shim. The Shim boot support trusts attacker-controlled values when parsing an HTTP response. This flaw allows an attacker to craft a specific malicious HTTP request, leading to a completely controlled out-of-bounds write primitive and complete system compromise. This flaw is only exploitable during the early boot phase, an attacker needs to perform a Man-in-the-Middle or compromise the boot server to be able to exploit this vulnerability successfully.\n\n## Affected\n\n- `shim < 15.8`\n- `enterprise_linux = 7.0`\n- `enterprise_linux = 8.0`\n- `enterprise_linux = 9.0`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `shim 15.8`","depth":"twilight","depthScore":47,"depthScoreParts":{"impact":45.7,"likelihood":1.1,"exploitation":0,"ransomware":0},"changes":[]}