# CVE-2026-25734: Rucio WebUI has Stored Cross-site Scripting (XSS) in RSE Metadata

> Attackers can inject malicious scripts into Rucio WebUI RSE metadata, leading to arbitrary JavaScript execution and potential session theft for viewing users.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 25 Feb 2026
- **Updated:** 26 Feb 2026
- **Also known as:** GHSA-h9fp-p2p9-873q, PYSEC-2026-3057

## What is CVE-2026-25734?

CVE-2026-25734 is a medium-severity cross-site scripting vulnerability in rucio, published on 25 Feb 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official description

Rucio is a software framework that provides functionality to organize, manage, and access large volumes of scientific data using customizable policies. Versions prior to 35.8.3, 38.5.4, and 39.3.1 have a stored Cross-Site Scripting (XSS) vulnerability in the RSE metadata of the WebUI where attacker-controlled input is persisted by the backend and later rendered in the WebUI without proper output encoding. This allows arbitrary JavaScript execution in the context of the WebUI for users who view affected pages, potentially enabling session token theft or unauthorized actions. Versions 35.8.3, 38.5.4, and 39.3.1 fix the issue.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation), CWE-1004 (Sensitive Cookie Without 'HttpOnly' Flag)

## Which versions are affected by CVE-2026-25734?

7 open source packages ship an affected version, including rucio-webui. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `rucio-webui` | PyPI | All versions | 35.8.3, 38.5.4, 39.3.1 |
| `rucio-webui` | PyPI | All versions | 35.8.3 |
| `rucio-webui` | PyPI | All versions | 35.8.3 |
| `rucio-webui` | PyPI | From 36.0.0rc1 | 38.5.4 |
| `rucio-webui` | PyPI | From 36.0.0rc1 | 38.5.4 |
| `rucio-webui` | PyPI | From 39.0.0rc1 | 39.3.1 |
| `rucio-webui` | PyPI | From 39.0.0rc1 | 39.3.1 |

Products: Cern Rucio.

## How do I fix CVE-2026-25734?

Upgrade rucio-webui to a fixed version for your release line: 35.8.3, 38.5.4 or 39.3.1.

## Is CVE-2026-25734 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-25734 exists.

## Other vulnerabilities in rucio

- [CVE-2026-29080](https://insights.sbomify.com/CVE-2026-29080/): Rucio SQL Injection in FilterEngine Oracle JSON Path via DID Search API (critical 9.4)
- [CVE-2026-29090](https://insights.sbomify.com/CVE-2026-29090/): Rucio SQL injection in postgres_meta DID search path compromises PostgreSQL metadata database (critical 9.0)
- [CVE-2026-25136](https://insights.sbomify.com/CVE-2026-25136/): Rucio WebUI has a Reflected Cross-site Scripting Vulnerability (high 8.1)
- [CVE-2026-25733](https://insights.sbomify.com/CVE-2026-25733/): Rucio WebUI Vulnerable to Stored Cross-site Scripting (XSS) through Custom Rule Function (high 7.3)
- [CVE-2026-25735](https://insights.sbomify.com/CVE-2026-25735/): Rucio WebUI has a Stored Cross-site Scripting (XSS) vulnerability its Identity Name (medium 6.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-25734 and fix it if it is affected.

What it is: CVE-2026-25734 is a medium-severity cross-site scripting vulnerability in rucio, published on 25 Feb 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-25734 exists.

Affected packages and fixed versions:
- rucio-webui (PyPI): affected all versions; fixed in 35.8.3, 38.5.4, 39.3.1
- rucio-webui (PyPI): affected all versions; fixed in 35.8.3
- rucio-webui (PyPI): affected all versions; fixed in 35.8.3
- rucio-webui (PyPI): affected from 36.0.0rc1; fixed in 38.5.4
- rucio-webui (PyPI): affected from 36.0.0rc1; fixed in 38.5.4
- rucio-webui (PyPI): affected from 39.0.0rc1; fixed in 39.3.1
- rucio-webui (PyPI): affected from 39.0.0rc1; fixed in 39.3.1

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-2026-25734/ (Markdown: https://insights.sbomify.com/CVE-2026-25734/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-25734
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-25734
- OSV: https://osv.dev/vulnerability/CVE-2026-25734

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-25734/
Summaries are generated and may contain mistakes; the official description above is the record.