GS1920-24v2 firmware: Improper Check for Unusual or Exceptional Conditions
CVE-2022-43393 is a high-severity improper check for unusual or exceptional conditions vulnerability in GS1920-24v2 firmware from Zyxel, with a CVSS 3.1 base score of 8.2 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected GS1920-24v2 firmware versions: < V4.70(ABMH.8)C0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.6% 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
- Update Gs1350-6hp Firmware to 4.70\(abpi.5\)c0 or a later version.
- Update Gs1350-12hp Firmware to 4.70\(abpj.5\)c0 or a later version.
- Update Gs1350-18hp Firmware to 4.70\(abpk.5\)c0 or a later version.
- Read the advisory on zyxel.com for workarounds and exact fixed builds.
- 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 |
|---|---|---|---|
| Zyxel | GS1920-24v2 firmware | < V4.70(ABMH.8)C0 | Not stated |
| Zyxel | Gs1350-6hp Firmware | before 4.70\(abpi.5\)c0 | 4.70\(abpi.5\)c0 |
| Zyxel | Gs1350-12hp Firmware | before 4.70\(abpj.5\)c0 | 4.70\(abpj.5\)c0 |
| Zyxel | Gs1350-18hp Firmware | before 4.70\(abpk.5\)c0 | 4.70\(abpk.5\)c0 |
| Zyxel | Gs1350-26hp Firmware | before 4.70\(abpl.5\)c0 | 4.70\(abpl.5\)c0 |
| Zyxel | Gs1915-8 Firmware | before 4.70\(acap.3\)c0 | 4.70\(acap.3\)c0 |
| Zyxel | Gs1915-8ep Firmware | before 4.70\(acaq.3\)c0 | 4.70\(acaq.3\)c0 |
| Zyxel | Gs1915-24e Firmware | before 4.70\(acdr.3\)c0 | 4.70\(acdr.3\)c0 |
| Zyxel | Gs1915-24ep Firmware | before 4.70\(acds.3\)c0 | 4.70\(acds.3\)c0 |
| Zyxel | Gs1920-48v2 Firmware | before 4.70\(abmj.8\)c0 | 4.70\(abmj.8\)c0 |
| Zyxel | Gs1920-24hpv2 Firmware | before 4.70\(abmi.8\)c0 | 4.70\(abmi.8\)c0 |
| Zyxel | Gs1920-48hpv2 Firmware | before 4.70\(abmk.8\)c0 | 4.70\(abmk.8\)c0 |
| Zyxel | Gs2220-10 Firmware | before 4.70\(abro.6\)c0 | 4.70\(abro.6\)c0 |
| Zyxel | Gs2220-28 Firmware | before 4.70\(abrq.6\)c0 | 4.70\(abrq.6\)c0 |
| Zyxel | Gs2220-50 Firmware | before 4.70\(abrs.6\)c0 | 4.70\(abrs.6\)c0 |
| Zyxel | Gs2220-10hp Firmware | before 4.70\(abrp.6\)c0 | 4.70\(abrp.6\)c0 |
| Zyxel | Gs2220-28hp Firmware | before 4.70\(abrr.6\)c0 | 4.70\(abrr.6\)c0 |
| Zyxel | Gs2220-50hp Firmware | before 4.70\(abrt.6\)c0 | 4.70\(abrt.6\)c0 |
| Zyxel | Xgs1930-28 Firmware | before 4.70\(abht.5\)c0 | 4.70\(abht.5\)c0 |
| Zyxel | Xgs1930-28hp Firmware | before 4.70\(abhs.5\)c0 | 4.70\(abhs.5\)c0 |
| Zyxel | Xgs1930-52 Firmware | before 4.70\(abhu.5\)c0 | 4.70\(abhu.5\)c0 |
| Zyxel | Xgs1930-52hp Firmware | before 4.70\(abhv.5\)c0 | 4.70\(abhv.5\)c0 |
| Zyxel | Xs1930-10 Firmware | before 4.80\(abqe.0\)c0 | 4.80\(abqe.0\)c0 |
| Zyxel | Xs1930-12hp Firmware | before 4.80\(abqf.0\)c0 | 4.80\(abqf.0\)c0 |
| Zyxel | Xs1930-12f Firmware | before 4.80\(abzv.0\)c0 | 4.80\(abzv.0\)c0 |
Version data comes from the organisation that assigned the CVE; 20 further products are omitted here. 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
- LowNo special conditions are needed; the attack works reliably.
- 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
- NoneNo data is disclosed.
- Integrity
- LowLimited modification of data is possible.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.2 | High | CNA (zyxel.com.tw) |
| CVSS 3.1 | 8.2 | High | NVD |
Official description
An improper check for unusual or exceptional conditions in the HTTP request processing function of Zyxel GS1920-24v2 firmware prior to V4.70(ABMH.8)C0, which could allow an unauthenticated attacker to corrupt the contents of the memory and result in a denial-of-service (DoS) condition on a vulnerable device.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Check for Unusual or Exceptional Conditions
The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Choose languages with features such as exception handling that force the programmer to anticipate unusual conditions that may generate exceptions. Custom exceptions may need to be developed to handle unusual business-logic conditions. Be careful not to pass sensitive exceptions back to the user (CWE-209, CWE-248).
- Check the results of all functions that return a value and verify that the value is expected.
- If using exception handling, catch and throw specific exceptions instead of overly-general exceptions (CWE-396, CWE-397). Catch and handle exceptions as locally as possible so that exceptions do not propagate too far up the call stack (CWE-705). Avoid unchecked or uncaught exceptions where feasible (CWE-248).
More Improper Check for Unusual or Exceptional Conditions vulnerabilities (CWE-754)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Recent Improper Check for Unusual or Exceptional Conditions vulnerabilities
- 7.5 High severity
- 8.2 High severity
- 8.2 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
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