GNU GRUB: Integer Underflow (Wrap or Wraparound)
CVE-2022-28733 is a high-severity integer underflow (wrap or wraparound) vulnerability in GNU GRUB from GNU Project, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 2.06-3 as the first without the flaw, so updating GNU GRUB to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.27% chance of exploitation within 30 days, higher than 70% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update GNU GRUB to 2.06-3 or a later version.
- Update Grub2 to 2.06-3 or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| GNU Project | GNU GRUB | before 2.06-3 | 2.06-3 |
| GNU | Grub2 | 2.00 up to, but not including, 2.06-3 | 2.06-3 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.1 | High | CNA (ubuntu.com) |
| CVSS 3.1 | 8.1 | High | NVD |
Official description
Integer underflow in grub_net_recv_ip4_packets; A malicious crafted IP packet can lead to an integer underflow in grub_net_recv_ip4_packets() function on rsm->total_len value. Under certain circumstances the total_len value may end up wrapping around to a small integer number which will be used in memory allocation. If the attack succeeds in such way, subsequent operations can write past the end of the buffer.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Underflow (Wrap or Wraparound)
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
More Integer Underflow (Wrap or Wraparound) vulnerabilities (CWE-191)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-28733Third Party Advisory
- openwall.com/lists/oss-security/2022/06/07/5Mailing List, Third Party Advisory
Other references
Other vulnerabilities in GNU GRUB
- 7.8 High severity
- 7.0 High severity
Recent Integer Underflow (Wrap or Wraparound) vulnerabilities
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.8 High severity
Spotted an error? Tell us.