PatchTheCVECVE-2023-26158: All versions of the package mockjs are vulnerable to Prototype Pollution via the Util.extend function due to m
CVE-2023-26158 is a high-severity flaw (CVSS 8.2) affecting mock.js. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
All versions of the package mockjs are vulnerable to Prototype Pollution via the Util.extend function due to missing check if the attribute resolves to the object prototype. By adding or modifying attributes of an object prototype, it is possible to create attributes that exist on every object, or replace critical attributes with malicious ones. This can be problematic if the software depends on existence or non-existence of certain attributes, o
Why this priority
- High severity
- Public exploit reference
- Remotely exploitable, no login, no user action
A fixed release or distro patch exists.
Risk facts
| CVSS score | 8.2 (High) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.8% (top 43%) |
| CISA exploited list | No |
| Weakness | CWE-1321 |
| Published | 2023-12-08 |
| Last modified | 2026-06-17 |
Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Quick answers
How do I fix CVE-2023-26158?
mock.js: upgrade to newer than 1.1.0. Exact commands for each OS are on this page.
Is CVE-2023-26158 being exploited?
CVE-2023-26158 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.
What does CVE-2023-26158 affect?
CVE-2023-26158 affects mock.js. Severity is high (CVSS 8.2). All versions of the package mockjs are vulnerable to Prototype Pollution via the Util.extend function due to missing check if the attribute resolves to the object prototype. By adding or modifying attributes of an object prototype, it is po
How urgent is CVE-2023-26158?
Priority 53/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action