# CVE-2020-23259: Null dereference in n/a

> An attacker can cause a denial of service in Jsish via a null pointer dereference in the Jsi_Strlen function.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 4 Apr 2023
- **Updated:** 14 Feb 2025
- **Also known as:** GHSA-8g46-vcjj-g5qj

## What is CVE-2020-23259?

CVE-2020-23259 is a high-severity vulnerability in Jsish Jsish, published on 4 Apr 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue found in Jsish v.3.0.11 and before allows an attacker to cause a denial of service via the Jsi_Strlen function in the src/jsiChar.c file.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2020-23259?

It affects 1 product.


Products: Jsish Jsish.

## How do I fix CVE-2020-23259?

No fix has been published for CVE-2020-23259 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-23259 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-23259 exists.

## Other vulnerabilities in Jsish Jsish

- [CVE-2025-65570](https://insights.sbomify.com/CVE-2025-65570/): Memory corruption in n/a (critical 9.8)
- [CVE-2024-24186](https://insights.sbomify.com/CVE-2024-24186/): Denial of service in n/a (critical 9.8)
- [CVE-2024-24188](https://insights.sbomify.com/CVE-2024-24188/): Memory corruption in n/a (critical 9.8)
- [CVE-2024-24189](https://insights.sbomify.com/CVE-2024-24189/): Use after free in n/a (critical 9.8)
- [CVE-2020-22873](https://insights.sbomify.com/CVE-2020-22873/): Memory corruption in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-23259 and fix it if it is affected.

What it is: CVE-2020-23259 is a high-severity vulnerability in Jsish Jsish, published on 4 Apr 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-23259 exists.

Affected product: Jsish Jsish. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2020-23259/ (Markdown: https://insights.sbomify.com/CVE-2020-23259/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-23259
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-23259
- OSV: https://osv.dev/vulnerability/CVE-2020-23259

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-23259/
Summaries are generated and may contain mistakes; the official description above is the record.