# CVE-2026-43633: HestiaCP 1.9.0-1.9.4 Deserialization RCE via Web Terminal

> Unauthenticated attackers can achieve root-level code execution via deserialization in the web terminal component when enabled.

- **Severity:** Critical 9.5 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 May 2026
- **Updated:** 14 Jul 2026
- **Also known as:** GHSA-p57r-8pg4-2892

## What is CVE-2026-43633?

CVE-2026-43633 is a critical unsafe deserialization vulnerability in hestiacp, published on 19 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

HestiaCP versions 1.9.0 through 1.9.4 contain a deserialization vulnerability in the web terminal component caused by a session format mismatch between PHP and Node.js that allows unauthenticated remote attackers to achieve root-level code execution. Attackers can inject crafted data into HTTP headers that are processed by the PHP session handler but incorrectly deserialized by the Node.js web terminal component as trusted session values, resulting in arbitrary command execution on systems with the web terminal feature enabled.

Weakness: CWE-502 (Deserialization of Untrusted Data)

## Which versions are affected by CVE-2026-43633?


## How do I fix CVE-2026-43633?

No fix has been published for CVE-2026-43633 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-43633 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-43633 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-43633 and fix it if it is affected.

What it is: CVE-2026-43633 is a critical unsafe deserialization vulnerability in hestiacp, published on 19 May 2026. 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-2026-43633 exists.

Affected product: hestiacp. 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-2026-43633/ (Markdown: https://insights.sbomify.com/CVE-2026-43633/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-43633
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-43633
- OSV: https://osv.dev/vulnerability/CVE-2026-43633

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-43633/
Summaries are generated and may contain mistakes; the official description above is the record.