# CVE-2023-40548: shim: A buffer overflow was found in Shim in the 32-bit system CVE-2023-40548 is fixed in 5 products on 1 platform, first by shim 15.8-0ubuntu1, released January 22, 2024. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2023-40548 - Priority: High - CVSS: 7.4 (high) - EPSS: 0.0044 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Jan 22, 2024 ## Description A buffer overflow was found in Shim in the 32-bit system. The overflow happens due to an addition operation involving a user-controlled value parsed from the PE binary being used by Shim. This value is further used for memory allocation operations, leading to a heap-based buffer overflow. This flaw causes memory corruption and can lead to a crash or data integrity issues during the boot phase. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | shim Debian 12.15 (bookworm) | 15.8-1~deb12u1 | [DEBIAN-CVE-2023-40548](https://patchblox.com/security/data/fix/linux/debian-cve-2023-40548.md) | Jan 29, 2024 | | Linux | shim Debian 13.5 (trixie) | 15.8-1 | [DEBIAN-CVE-2023-40548](https://patchblox.com/security/data/fix/linux/debian-cve-2023-40548.md) | Jan 29, 2024 | | Linux | shim Debian 14 | 15.8-1 | [DEBIAN-CVE-2023-40548](https://patchblox.com/security/data/fix/linux/debian-cve-2023-40548.md) | Jan 29, 2024 | | Linux | shim Ubuntu 20.04 LTS (focal) | 15.8-0ubuntu1 | [shim 15.8-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-shim-15.8-0ubuntu1.md) | Jan 22, 2024 | | Linux | shim Ubuntu 22.04.1 LTS (jammy) | 15.8-0ubuntu1 | [shim 15.8-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-shim-15.8-0ubuntu1.md) | Jan 22, 2024 | | Linux | shim Ubuntu 24.04.5 LTS (noble) | 15.8-0ubuntu1 | [shim 15.8-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-shim-15.8-0ubuntu1.md) | Jan 22, 2024 | | Linux | shim Ubuntu 24.10 (oracular) | 15.8-0ubuntu1 | [shim 15.8-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-shim-15.8-0ubuntu1.md) | Jan 23, 2024 | | Linux | shim Ubuntu 25.04 (plucky) | 15.8-0ubuntu1 | [shim 15.8-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-shim-15.8-0ubuntu1.md) | Jan 23, 2024 | | Linux | shim-aa64 RHEL 8 | 0:15.8-4.el8_9 | [RHSA-2024:1902](https://patchblox.com/security/data/fix/linux/rhsa-2024-1902.md) | Apr 18, 2024 | | Linux | shim-aa64 RHEL 9 | 0:15.8-4.el9_3 | [RHSA-2024:1903](https://patchblox.com/security/data/fix/linux/rhsa-2024-1903.md) | Apr 18, 2024 | | Linux | shim-aa64 almalinux 8 | 15.8-4.el8_9.alma.1 | [ALSA-2024:1902](https://patchblox.com/security/data/fix/linux/alsa-2024-1902.md) | Apr 18, 2024 | | Linux | shim-aa64 almalinux 9 | 15.8-4.el9_3.alma.1 | [ALSA-2024:1903](https://patchblox.com/security/data/fix/linux/alsa-2024-1903.md) | Apr 18, 2024 | | Linux | shim-aa64 ol 8 | 0:15.8-4.0.1.el8 | [ELSA-2024-1902](https://patchblox.com/security/data/fix/linux/elsa-2024-1902.md) | Apr 25, 2024 | | Linux | shim-aa64 ol 9 | 0:15.8-1.0.3.el9 | [ELSA-2024-1903](https://patchblox.com/security/data/fix/linux/elsa-2024-1903.md) | Apr 22, 2024 | | Linux | shim-ia32 RHEL 8 | 0:15.8-4.el8_9 | [RHSA-2024:1902](https://patchblox.com/security/data/fix/linux/rhsa-2024-1902.md) | Apr 18, 2024 | | Linux | shim-ia32 almalinux 8 | 15.8-4.el8_9.alma.1 | [ALSA-2024:1902](https://patchblox.com/security/data/fix/linux/alsa-2024-1902.md) | Apr 18, 2024 | | Linux | shim-ia32 ol 8 | 0:15.8-4.0.1.el8 | [ELSA-2024-1902](https://patchblox.com/security/data/fix/linux/elsa-2024-1902.md) | Apr 25, 2024 | | Linux | shim-signed Ubuntu 20.04 LTS (focal) | 1.40.10+15.8-0ubuntu1 | [shim-signed 1.40.10+15.8-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-shim-signed-1.40.10-15.8-0ubuntu1.md) | Jan 22, 2024 | | Linux | shim-signed Ubuntu 22.04.1 LTS (jammy) | 1.51.4+15.8-0ubuntu1 | [shim-signed 1.51.4+15.8-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-shim-signed-1.51.4-15.8-0ubuntu1.md) | Jan 22, 2024 | | Linux | shim-signed Ubuntu 24.04.5 LTS (noble) | 1.58+15.8-0ubuntu1 | [shim-signed 1.58+15.8-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-shim-signed-1.58-15.8-0ubuntu1.md) | Jan 22, 2024 | | Linux | shim-signed Ubuntu 24.10 (oracular) | 1.58+15.8-0ubuntu1 | [shim-signed 1.58+15.8-0ubuntu1](https://patchblox.com/security/data/fix/linux/ubuntu-oracular-shim-signed-1.58-15.8-0ubuntu1.md) | Jan 23, 2024 | | Linux | shim-signed Ubuntu 25.04 (plucky) | 1.58 | [shim-signed 1.58](https://patchblox.com/security/data/fix/linux/ubuntu-plucky-shim-signed-1.58.md) | Jan 23, 2024 | | Linux | shim-x64 RHEL 8 | 0:15.8-4.el8_9 | [RHSA-2024:1902](https://patchblox.com/security/data/fix/linux/rhsa-2024-1902.md) | Apr 18, 2024 | | Linux | shim-x64 RHEL 9 | 0:15.8-4.el9_3 | [RHSA-2024:1903](https://patchblox.com/security/data/fix/linux/rhsa-2024-1903.md) | Apr 18, 2024 | | Linux | shim-x64 almalinux 8 | 15.8-4.el8_9.alma.1 | [ALSA-2024:1902](https://patchblox.com/security/data/fix/linux/alsa-2024-1902.md) | Apr 18, 2024 | | Linux | shim-x64 almalinux 9 | 15.8-4.el9_3.alma.1 | [ALSA-2024:1903](https://patchblox.com/security/data/fix/linux/alsa-2024-1903.md) | Apr 18, 2024 | | Linux | shim-x64 ol 8 | 0:15.8-4.0.1.el8 | [ELSA-2024-1902](https://patchblox.com/security/data/fix/linux/elsa-2024-1902.md) | Apr 25, 2024 | | Linux | shim-x64 ol 9 | 0:15.8-1.0.3.el9 | [ELSA-2024-1903](https://patchblox.com/security/data/fix/linux/elsa-2024-1903.md) | Apr 22, 2024 | --- Data as of 2026-11-08T06:59:42Z UTC. 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