PatchTheCVECVE-2023-40547: A remote code execution vulnerability was found in Shim
CVE-2023-40547 is a high-severity flaw (CVSS 8.3) affecting shim, enterprise linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
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 serve
Why this priority
- High severity
- EPSS top 7%: very likely to be exploited
- On your watchlist
A fixed release or distro patch exists.
Last updated 2026-06-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2023-40547?
shim: upgrade to 15.8; enterprise linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.
Is CVE-2023-40547 being exploited?
CVE-2023-40547 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2023-40547 affect?
CVE-2023-40547 affects shim, enterprise linux. Severity is high (CVSS 8.3). 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
How urgent is CVE-2023-40547?
Priority 57/100. High severity; EPSS top 7%: very likely to be exploited; On your watchlist
Related CVEs
- CVE-2023-40548 HIGH 7.4 UPGRADE MITIGATE A buffer overflow was found in Shim in the 32-bit system
- CVE-2023-40551 MEDIUM 5.1 UPGRADE MITIGATE A flaw was found in the MZ binary format in Shim
- CVE-2023-40550 MEDIUM 5.5 UPGRADE MITIGATE An out-of-bounds read flaw was found in Shim when it tried to validate the SBAT information
- CVE-2023-40549 MEDIUM 6.2 UPGRADE MITIGATE An out-of-bounds read flaw was found in Shim due to the lack of proper boundary verification during the load o
- CVE-2023-40546 MEDIUM 6.2 UPGRADE MITIGATE A flaw was found in Shim when an error happened while creating a new ESL variable