A920: Improper Neutralization of Special Elements in Output Used by a Downstream Component
CVE-2023-4818 is a high-severity improper neutralization of special elements in output used by a downstream component vulnerability in A920 from PAX Technology, with a CVSS 3.1 base score of 7.6 out of 10. It can be exploited with physical access to the device by an unauthenticated attacker, without any action from a user. The record lists version A920_AP_Boot_Release_V5.14 as the first without the flaw, so updating A920 to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.66% chance of exploitation within 30 days, higher than 52% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update A920 to A920_AP_Boot_Release_V5.14 or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| PAX Technology | A920 | before A920_AP_Boot_Release_V5.14 | A920_AP_Boot_Release_V5.14 |
| Paxtechnology | Paydroid | 7.1.2_aquarius_11.1.50_20230614 | 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
- PhysicalThe attacker must physically touch the device.
- 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
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- 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:P/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.6 | High | NVD |
| CVSS 3.1 | 7.6 | High | CISA (ADP) |
Official description
PAX A920 device allows to downgrade bootloader due to a bug in its version check. The signature is correctly checked and only bootloader signed by PAX can be used. The attacker must have physical USB access to the device in order to exploit this vulnerability.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Neutralization of Special Elements in Output Used by a Downstream Component
The product constructs all or part of a command, data structure, or record using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify how it is parsed or interpreted when it is sent to a downstream component.
How developers prevent this class of flaw
- Programming languages and supporting technologies might be chosen which are not subject to these issues.
- Utilize an appropriate mix of allowlist and denylist parsing to filter control-plane syntax from all input.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- cert.pl/en/posts/2024/01/CVE-2023-4818/Third Party Advisory
- cert.pl/posts/2024/01/CVE-2023-4818/Third Party Advisory
Technical write-ups (may include proof of concept)
- blog.stmcyber.com/pax-pos-cves-2023/Exploit, Third Party Advisory
Other references
- ppn.paxengine.com/release/developmentPermissions Required
Recent Improper Neutralization of Special Elements in Output Used by a Downstream Component vulnerabilities
- 7.8 High severity
- 9.8 Critical severity
- 7.5 High severity
- 9.6 Critical severity
- 9.6 Critical severity
- 9.8 Critical severity
Spotted an error? Tell us.