USG FLEX 100(W) firmware: Improper Privilege Management
CVE-2022-30526 is a high-severity improper privilege management vulnerability in USG FLEX 100(W) firmware from Zyxel, 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 USG FLEX 100(W) firmware versions: 4.50 through 5.30. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 1.14% chance of exploitation within 30 days, higher than 67% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of USG FLEX 100(W) firmware you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on zyxel.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Zyxel | USG FLEX 100(W) firmware | 4.50 through 5.30 | Not stated |
| Zyxel | USG FLEX 200 firmware | 4.50 through 5.30 | Not stated |
| Zyxel | USG FLEX 500 firmware | 4.50 through 5.30 | Not stated |
| Zyxel | USG FLEX 700 firmware | 4.50 through 5.30 | Not stated |
| Zyxel | ATP series firmware | 4.32 through 5.30 | Not stated |
| Zyxel | VPN series firmware | 4.30 through 5.30 | Not stated |
| Zyxel | USG FLEX 50(W) firmware | 4.16 through 5.30 | Not stated |
| Zyxel | USG 20(W)-VPN firmware | 4.16 through 5.30 | Not stated |
| Zyxel | USG/ZyWALL series firmware | 4.09 through 4.72 | Not stated |
| Zyxel | Usg Flex 100w Firmware | 4.50 through 5.30 | Not stated |
| Zyxel | Usg Flex 50w Firmware | 4.16 through 5.30 | Not stated |
| Zyxel | Usg20w-vpn Firmware | 4.16 through 5.30 | Not stated |
| Zyxel | Atp800 Firmware | 4.32 through 5.30 | Not stated |
| Zyxel | Atp700 Firmware | 4.32 through 5.30 | Not stated |
| Zyxel | Atp500 Firmware | 4.32 through 5.30 | Not stated |
| Zyxel | Atp200 Firmware | 4.32 through 5.30 | Not stated |
| Zyxel | Atp100w Firmware | 4.32 through 5.30 | Not stated |
| Zyxel | Atp100 Firmware | 4.32 through 5.30 | Not stated |
| Zyxel | Vpn1000 Firmware | 4.30 through 5.30 | Not stated |
| Zyxel | Vpn300 Firmware | 4.30 through 5.30 | Not stated |
| Zyxel | Vpn100 Firmware | 4.30 through 5.30 | Not stated |
| Zyxel | Vpn50 Firmware | 4.30 through 5.30 | Not stated |
| Zyxel | Usg20-vpn Firmware | 4.30 through 5.30 | Not stated |
| Zyxel | Usg 2200-vpn Firmware | 4.30 through 5.30 | Not stated |
| Zyxel | Zywall 110 Firmware | 4.30 through 5.30 | Not stated |
Version data comes from the organisation that assigned the CVE; 6 further products are omitted here. 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 | 7.8 | High | CNA (zyxel.com.tw) |
| CVSS 3.1 | 7.8 | High | NVD |
Official description
A privilege escalation vulnerability was identified in the CLI command of Zyxel USG FLEX 100(W) firmware versions 4.50 through 5.30, USG FLEX 200 firmware versions 4.50 through 5.30, USG FLEX 500 firmware versions 4.50 through 5.30, USG FLEX 700 firmware versions 4.50 through 5.30, USG FLEX 50(W) firmware versions 4.16 through 5.30, USG20(W)-VPN firmware versions 4.16 through 5.30, ATP series firmware versions 4.32 through 5.30, VPN series firmware versions 4.30 through 5.30, USG/ZyWALL series firmware versions 4.09 through 4.72, which could allow a local attacker to execute some OS commands with root privileges in some directories on a vulnerable device.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Privilege Management
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.
How developers prevent this class of flaw
- Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
- Follow the principle of least privilege when assigning access rights to entities in a software system.
- Consider following the principle of separation of privilege. Require multiple conditions to be met before permitting access to a system resource.
More Improper Privilege Management vulnerabilities (CWE-269)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Technical write-ups (may include proof of concept)
- packetstormsecurity.com/files/168202/Zyxel-Firewall-SUID-Binary-Privilege-Escalation.htmlExploit, Third Party Advisory, VDB Entry
Other vulnerabilities in USG FLEX 100(W) firmware
- 9.8 Critical severity
Recent Improper Privilege Management vulnerabilities
- 7.1 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.2 High severity
- 7.5 High severity
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