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CVE-2015-8370

21
FAUCET Score

CVE-2015-8370 describes multiple integer underflows in Grub2 versions 1.98 through 2.02, affecting Fedora and GNU Grub2 products. This vulnerability allows physically proximate attackers to bypass authentication, access sensitive information, or cause disk corruption by using backspace characters in username or password input fields. With a CVSS score of 7.4 (HIGH), the attack requires physical access but is complex to execute, leading to high impacts on confidentiality, integrity, and availability. While there is no known active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB) is unavailable, and it is not listed in the KEV catalog. Despite this, the vulnerability has garnered significant community attention and media coverage, indicating its potential risk.

Impacted Technologies

VendorProductVersion(s)CPE
1.98CPE matchmatch criteria
cpe:2.3:a:gnu:grub2:1.98:*:*:*:*:*:*:*
1.99CPE matchmatch criteria
cpe:2.3:a:gnu:grub2:1.99:*:*:*:*:*:*:*
2.00CPE matchmatch criteria
cpe:2.3:a:gnu:grub2:2.00:*:*:*:*:*:*:*
2.01CPE matchmatch criteria
cpe:2.3:a:gnu:grub2:2.01:*:*:*:*:*:*:*
2.02CPE matchmatch criteria
cpe:2.3:a:gnu:grub2:2.02:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 2.0

6.9MEDIUM

AV:L/AC:M/Au:N/C:C/I:C/A:C

Confidentiality Impact
COMPLETE
Integrity Impact
COMPLETE
Availability Impact
COMPLETE
Access Vector
LOCAL
Access Complexity
MEDIUM
Authentication
NONE
Exploitability Score
3.4
Impact Score
10.0
CvssVersion
2.0

Exploit Intelligence

EPSS Score
1.10%
Probability of exploitation in next 30 days
EPSS Percentile
62.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0110 is in the 94th percentile among its peer group of 157 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.2 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (6)

microsoftpatch availablevia msrc
Product: cm1 grub2 2.02-24 on CBL Mariner 1.0Fixed in: 2.02-24
microsoftpatch availablevia msrc
Product: 16850-16820Fixed in: 2.02-24
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 x64Fixed in: 2.02-24
microsoftpatch availablevia msrc
Product: CBL Mariner 1.0 ARMFixed in: 2.02-24
oraclepatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Enterprise Linux 7Fixed in: grub2-1:2.02-0.33.el7_2
View patch

Vendor Advisories (3)

microsoft2020-Aug/CVE-2015-8370

CVE-2015-8370

Aug 11, 2020
redhatCVE-2015-8370Moderate

grub2: buffer overflow when checking password entered during bootup

Dec 10, 2015
microsoft2015-Dec/CVE-2015-8370Moderate

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.

Dec 2, 2015

References

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