CVE-2023-40547
Shim: rce in http boot support may lead to secure boot bypass
- Published
- Updated
- Reserved
- Assigned by
- redhat
Description
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 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.
Timeline
ID reserved
By redhat
- 5 months later
· 5 months later
Published
- 2 years later
· 2 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| redhatCNA (assigner) | 3.1 | High8.3 | CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H |
| NVDNVD · Modified | 3.1 | High8.3 | CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 5.4% · top 7.3% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.3.
Weakness
Affected products
Red Hat · Red Hat Enterprise Linux 7
- unaffected 0:15.8-3.el7 – < *
Red Hat · Red Hat Enterprise Linux 7
- unaffected 0:15.8-1.el7 – < *
Red Hat · Red Hat Enterprise Linux 8
- unaffected 0:15.8-4.el8_9 – < *
Red Hat · Red Hat Enterprise Linux 8.2 Advanced Update Support
- unaffected 0:15.8-2.el8_2 – < *
Red Hat · Red Hat Enterprise Linux 8.2 Telecommunications Update Service
- unaffected 0:15.8-2.el8_2 – < *
Red Hat · Red Hat Enterprise Linux 8.2 Update Services for SAP Solutions
- unaffected 0:15.8-2.el8_2 – < *
Red Hat · Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
- unaffected 0:15.8-2.el8_4 – < *
Red Hat · Red Hat Enterprise Linux 8.4 Telecommunications Update Service
- unaffected 0:15.8-2.el8_4 – < *
Red Hat · Red Hat Enterprise Linux 8.4 Update Services for SAP Solutions
- unaffected 0:15.8-2.el8_4 – < *
Red Hat · Red Hat Enterprise Linux 8.6 Extended Update Support
- unaffected 0:15.8-2.el8_6 – < *
Red Hat · Red Hat Enterprise Linux 8.8 Extended Update Support
- unaffected 0:15.8-2.el8 – < *
Red Hat · Red Hat Enterprise Linux 8.8 Extended Update Support
- unaffected 0:15.8-2.el8 – < *
Red Hat · Red Hat Enterprise Linux 9
- unaffected 0:15.8-4.el9_3 – < *
Red Hat · Red Hat Enterprise Linux 9.0 Extended Update Support
- unaffected 0:15.8-3.el9 – < *
Red Hat · Red Hat Enterprise Linux 9.0 Extended Update Support
- unaffected 0:15.8-2.el9 – < *
Red Hat · Red Hat Enterprise Linux 9.0 Extended Update Support
- unaffected 0:15.8-2.el9 – < *
Red Hat · Red Hat Enterprise Linux 9.2 Extended Update Support
- unaffected 0:15.8-3.el9_2 – < *
What to do
Workaround: If a system isn’t required to boot from the network, configure the server’s boot order to disable entirely or skip the network boot.
References (13)
- RHSA-2024:1834 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2024:1835 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2024:1873 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2024:1876 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2024:1883 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2024:1902 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2024:1903 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2024:1959 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- RHSA-2024:2086 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
- https://access.redhat.com/security/cve/CVE-2023-40547 (opens in a new tab)vdb-entryx_refsource_REDHATx_transferred
- RHBZ#2234589 (opens in a new tab)issue-trackingx_refsource_REDHATx_transferred
- http://www.openwall.com/lists/oss-security/2024/01/26/1 (opens in a new tab)x_transferred
- https://lists.debian.org/debian-lts-announce/2024/05/msg00009.html (opens in a new tab)x_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2023-40547)Record last updated .