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Fencer Intel
high 7.4

CVE-2015-8370 json

Multiple integer underflows in Grub2 1.98 through 2.02 allow physically proximate attackers to bypass authentication, obtain sensitive info…

published 2015-12-16 10 y ago modified 2026-06-17 4 mo ago also EUVD-2015-8254

cvss
7.4
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.1%
EPSS 1.1% chance of exploitation in 30 days, percentile 65%
public exploits
0
none known

Summary

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.

Patch / fix

  • grub2 Debian 14, Debian 13, Debian 12 2.02~beta2-33

debian advisories DEBIAN-CVE-2015-8370

  • grub2 Ubuntu 14.04 LTS 2.02~beta2-9ubuntu1.6

ubuntu advisories UBUNTU-CVE-2015-8370

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • grub2 RHEL 7 1:2.02-0.33.el7_2
  • grub2-efi RHEL 7 1:2.02-0.33.el7_2
  • grub2-tools RHEL 7 1:2.02-0.33.el7_2
  • grub2-efi-modules RHEL 7 1:2.02-0.33.el7_2

red hat advisories RHSA-2015:2623

  • grub2 SLES for SAP 12, SLES 12, SLED 12 2.02~beta2-56.9.4
  • grub2 SLES for SAP 12 SP1, SLES 12 SP1, SLED 12 SP1 2.02~beta2-73.3
  • grub2 SLES for SAP 11 SP4, SLES 11 SP4, SLED 11 SP4 2.00-0.54.2
  • grub2 SLES for SAP 11 SP3, SLES 11 SP3-TERADATA, SLES 11 SP3 +1 more 2.00-0.49.2

suse advisories SUSE-SU-2015:2399-1SUSE-SU-2015:2387-1SUSE-SU-2015:2385-1SUSE-SU-2015:2386-1

  • grub2 openSUSE Tumbleweed 2.02~beta3-15.1

opensuse advisories openSUSE-SU-2024:10078-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2015-8370 updated cvss 6.9

grub2: buffer overflow when checking password entered during bootup

  • Red Hat Enterprise Linux Client (v. 7) grub2 2.02-0.33.el7_2, grub2-efi 2.02-0.33.el7_2, grub2-tools 2.02-0.33.el7_2 Red Hat Enterprise Linux Client Optional (v. 7) grub2-efi-modules 2.02-0.33.el7_2 Red Hat Enterprise Linux ComputeNode (v. 7) grub2 2.02-0.33.el7_2, grub2-efi 2.02-0.33.el7_2, grub2-tools 2.02-0.33.el7_2 Red Hat Enterprise Linux ComputeNode Optional (v. 7) grub2-efi-modules 2.02-0.33.el7_2 Red Hat Enterprise Linux Server (v. 7) grub2 2.02-0.33.el7_2, grub2-efi 2.02-0.33.el7_2, grub2-tools 2.02-0.33.el7_2 Red Hat Enterprise Linux Server Optional (v. 7) grub2-efi-modules 2.02-0.33.el7_2
    +2 more products
    Red Hat Enterprise Linux Workstation (v. 7) grub2 2.02-0.33.el7_2, grub2-efi 2.02-0.33.el7_2, grub2-tools 2.02-0.33.el7_2 Red Hat Enterprise Linux Workstation Optional (v. 7) grub2-efi-modules 2.02-0.33.el7_2
    fixed: vendor fix RHSA-2015:2623
  • Red Hat Enterprise Linux 5 grub Red Hat Enterprise Linux 6 grub Red Hat Enterprise Linux 8 grub2, grub2-pc, grub2-tools, grub2-common, grub2-efi-x64, grub2-ppc64le, +13 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
2 y ago

Exploit prediction

1.09% chance of exploitation in the next 30 days, higher than 65% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • hmarco.org http://hmarco.org/bugs/CVE-2015-8370-Grub2-authentication-bypass.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.4 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 7.4 CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 6.9 AV:L/AC:M/Au:N/C:C/I:C/A:C

Classification

Weakness
  • CWE-191 Integer Underflow (Wrap or Wraparound)
  • CWE-264 Permissions, Privileges, and Access Controls

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.