# CVE-2026-23929: Prototype pollution leading to stored XSS

> Attackers can inject malicious scripts via URL parameters in Zabbix Maps, leading to stored XSS and potential account takeover.

- **Severity:** High 8.5 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 18 Aug 2026
- **Updated:** 19 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-23929, GHSA-x27p-fpr7-4wpm, UBUNTU-CVE-2026-23929

## What is CVE-2026-23929?

CVE-2026-23929 is a high-severity cross-site scripting vulnerability in Zabbix Zabbix, published on 18 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Prototype pollution vulnerability in searchParamsToObject() is leading to a persistent XSS in Maps. URL parameter processing was not filtering dangerous properties like __proto__, combined with jQuery's unsafe element creation that traversed the prototype chain.

Weakness: CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes)

## Which versions are affected by CVE-2026-23929?

It affects 1 product.


Products: Zabbix Zabbix.

## How do I fix CVE-2026-23929?

Apply the vendor's patch.

## Is CVE-2026-23929 being exploited?

There is no known exploitation of CVE-2026-23929 in the wild and no public exploit code.

## Other vulnerabilities in Zabbix Zabbix

- [CVE-2022-23131](https://insights.sbomify.com/CVE-2022-23131/): Zabbix Frontend Authentication Bypass (critical 9.1, exploited in the wild)
- [CVE-2007-0640](https://insights.sbomify.com/CVE-2007-0640/): Memory corruption in n/a (critical 10.0)
- [CVE-2024-42327](https://insights.sbomify.com/CVE-2024-42327/): SQL injection in user.get API (critical 9.9)
- [CVE-2024-22116](https://insights.sbomify.com/CVE-2024-22116/): Remote code execution within ping script (critical 9.9)
- [CVE-2013-3738](https://insights.sbomify.com/CVE-2013-3738/): Code injection in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-23929 and fix it if it is affected.

What it is: CVE-2026-23929 is a high-severity cross-site scripting vulnerability in Zabbix Zabbix, published on 18 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-23929 in the wild and no public exploit code.

Affected product: Zabbix Zabbix. 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-2026-23929/ (Markdown: https://insights.sbomify.com/CVE-2026-23929/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-23929
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23929
- OSV: https://osv.dev/vulnerability/CVE-2026-23929

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-23929/
Summaries are generated and may contain mistakes; the official description above is the record.