Multiple integer underflows in Grub2 1.98 through 2.02 allow physically proximate attackers to bypass authentication, obtain sensitive infor
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.
- Published
- Dec 16, 2015
- Updated
- Jun 16, 2026
- EPSS
- 1.1% · 64th percentile
- CWE
- CWE-264
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Report tools
Action score
29
Monitor
Low priority for now.
- CVSS
- 29 / 40 · 7.4 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 1.1%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| gnu | grub2 | cpe:2.3:a:gnu:grub2 |
| fedoraproject | fedora | cpe:2.3:o:fedoraproject:fedora |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- fedoraproject fedora23
- gnu grub21.98
- gnu grub21.99
- gnu grub22.00
- gnu grub22.01
- gnu grub22.02
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | grub2 | before 2.02~beta2-33 | 2.02~beta2-33 |
| Debian:6.0 | grub2 | before 1.98+20100804-14+squeeze2 | 1.98+20100804-14+squeeze2 |
| Debian:7 | grub2 | before 1.99-27+deb7u3 | 1.99-27+deb7u3 |
| Debian:8 | grub2 | before 2.02~beta2-22+deb8u1 | 2.02~beta2-22+deb8u1 |
| openSUSE:Tumbleweed | grub2 | before 2.02~beta3-15.1 | 2.02~beta3-15.1 |
| Red Hat:enterprise_linux:7::client | grub2 | before 1:2.02-0.33.el7_2 | 1:2.02-0.33.el7_2 |
| Red Hat:enterprise_linux:7::client | grub2-debuginfo | before 1:2.02-0.33.el7_2 | 1:2.02-0.33.el7_2 |
| Red Hat:enterprise_linux:7::client | grub2-efi | before 1:2.02-0.33.el7_2 | 1:2.02-0.33.el7_2 |
| Red Hat:enterprise_linux:7::client | grub2-efi-modules | before 1:2.02-0.33.el7_2 | 1:2.02-0.33.el7_2 |
| Red Hat:enterprise_linux:7::client | grub2-tools | before 1:2.02-0.33.el7_2 | 1:2.02-0.33.el7_2 |
| SUSE:Linux Enterprise Desktop 11 SP3 | grub2 | before 2.00-0.49.2 | 2.00-0.49.2 |
| SUSE:Linux Enterprise Desktop 11 SP4 | grub2 | before 2.00-0.54.2 | 2.00-0.54.2 |
| SUSE:Linux Enterprise Desktop 12 | grub2 | before 2.02~beta2-56.9.4 | 2.02~beta2-56.9.4 |
| SUSE:Linux Enterprise Desktop 12 SP1 | grub2 | before 2.02~beta2-73.3 | 2.02~beta2-73.3 |
Same product
gnu: all recordsOther highest-scoring records for the same primary product.
- CVE-2024-56737GNU GRUB (aka GRUB2) through 2.12 has a heap-based buffer overflow in fs/hfs.c via crafted sblock data in an HFS filesystem.35Monitor
- CVE-2022-2601A buffer overflow was found in grub_font_construct_glyph().34Monitor
- CVE-2020-10713A flaw was found in grub2, prior to version 2.06.33Monitor
- CVE-2022-28733Integer underflow in grub_net_recv_ip4_packets32Monitor
- CVE-2021-20233A flaw was found in grub2 in versions prior to 2.06.32Monitor
- CVE-2020-25632A flaw was found in grub2 in versions prior to 2.06.32Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:grub2 | 2.02~beta2-33 · Debian:12 | Package registry (OSV) |
| opensuse:grub2 | 2.02~beta3-15.1 · openSUSE:Tumbleweed | Package registry (OSV) |
| red hat:grub2 | 1:2.02-0.33.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:grub2-debuginfo | 1:2.02-0.33.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:grub2-efi | 1:2.02-0.33.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:grub2-efi-modules | 1:2.02-0.33.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| red hat:grub2-tools | 1:2.02-0.33.el7_2 · Red Hat:enterprise_linux:7::client | Package registry (OSV) |
| suse:grub2 | 2.00-0.54.2 · SUSE:Linux Enterprise Desktop 11 SP4 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Someone with local access to the system can trigger it.
- No account or password is required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- high · data or configuration can be modified
- Availability
- high · the service can be disrupted
- Attack vector
- Local
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- High
- Availability impact
- High
Weakness class (CWE)
CWE-264 · Permissions, Privileges, and Access ControlsCVSS vector
CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- 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
- www.debian.org/security/2015/dsa-3421
- www.openwall.com/lists/oss-security/2015/12/15/6
- www.openwall.com/lists/oss-security/2024/01/15/3
- www.oracle.com/technetwork/topics/security/cpujan2016-2367955.html
- www.oracle.com/technetwork/topics/security/linuxbulletinoct2015-2719645.html
- www.securityfocus.com/archive/1/537115/100/0/threaded
- www.securityfocus.com/bid/79358
- www.securitytracker.com/id/1034422
Vendor advisories and official records. Exploit/PoC links are deliberately left out.