FortiProxy: Use of Externally-Controlled Format String
CVE-2022-43953 is a high-severity use of externally-controlled format string vulnerability in FortiProxy from Fortinet, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. Affected FortiProxy versions: 7.2.0 through 7.2.1; 7.0.0 through 7.0.7. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.25% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of FortiProxy you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on fortiguard.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Fortinet | FortiProxy | 7.2.0 through 7.2.1; 7.0.0 through 7.0.7 | Not stated |
| Fortinet | FortiOS | 7.2.0 through 7.2.4; 7.0.0 through 7.0.11; 6.4.0 through 6.4.12; 6.2.0 through 6.2.15 | Not stated |
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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- 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:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 6.7 | Medium | CNA (fortinet.com) |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
A use of externally-controlled format string in Fortinet FortiOS version 7.2.0 through 7.2.4, FortiOS all versions 7.0, FortiOS all versions 6.4, FortiOS all versions 6.2, FortiProxy version 7.2.0 through 7.2.1, FortiProxy version 7.0.0 through 7.0.7 allows attacker to execute unauthorized code or commands via specially crafted commands.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Externally-Controlled Format String
The product uses a function that accepts a format string as an argument, but the format string originates from an external source.
How developers prevent this class of flaw
- Choose a language that is not subject to this flaw.
- Ensure that all format string functions are passed a static string which cannot be controlled by the user, and that the proper number of arguments are always sent to that function as well. If at all possible, use functions that do not support the %n operator in format strings.
- Run compilers and linkers with high warning levels, since they may detect incorrect usage.
More Use of Externally-Controlled Format String vulnerabilities (CWE-134)
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
Advisories
Other vulnerabilities in FortiProxy
- 8.1 High severity
- 6.5 Medium severity
- 9.8 Critical severity
- 9.8 Critical severity
- 8.8 High severity
- 7.5 High severity
Recent Use of Externally-Controlled Format String vulnerabilities
- 9.8 Critical severity
- 7.8 High severity
- 8.8 High severity
- 7.8 High severity
- 8.5 High severity
- 9.8 Critical severity
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