# CVE-2026-81897: Concrete CMS below version 9.5.3 is vulnerable to Stored XSS via Express form Text control save_control

> Remote attackers can inject persistent JavaScript into Concrete CMS Express forms via CSRF, leading to code execution and potential account takeover for administrators.

- **Severity:** High 7.7 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 15 Sep 2026
- **Updated:** 22 Sep 2026
- **Also known as:** GHSA-m84f-3j8g-93wj

## What is CVE-2026-81897?

CVE-2026-81897 is a high-severity cross-site scripting vulnerability in Concretecms Concrete Cms, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

In Concrete CMS below CMS 9.5.3, the save_control action in the Express entities forms dashboard controller did not validate the anti-CSRF token. By causing an authenticated administrator to submit a forged cross-site request, a remote attacker without credentials could write attacker-controlled headline and body values to an existing Express form Text control. Those values were emitted without output encoding by the Express form Text element, so the injected markup executed as persistent JavaScript for any administrator who later opened the affected entry, resulting in stored cross-site scripting. The Concrete CMS security team gave this vulnerability a CVSS v4.0 score of 7.7 with vector CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N. Thanks Yonatan Drori from Tenzai for reporting.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation), CWE-352 (Cross-Site Request Forgery)

## Which versions are affected by CVE-2026-81897?

It affects 1 product.


Products: Concretecms Concrete Cms.

## How do I fix CVE-2026-81897?

No fix has been published for CVE-2026-81897 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-81897 being exploited?

There is no known exploitation of CVE-2026-81897 in the wild and no public exploit code.

## Other vulnerabilities in Concretecms Concrete Cms

- [CVE-2023-48648](https://insights.sbomify.com/CVE-2023-48648/): Concrete CMS allows unauthorized access because directories can be created with insecure permissions (critical 9.8)
- [CVE-2022-21829](https://insights.sbomify.com/CVE-2022-21829/): Code injection in concrete CMS (critical 9.8)
- [CVE-2021-22958](https://insights.sbomify.com/CVE-2021-22958/): Server-Side Request Forgery vulnerability in concrete5 (critical 9.8)
- [CVE-2021-40098](https://insights.sbomify.com/CVE-2021-40098/): Path traversal in n/a (critical 9.8)
- [CVE-2026-8134](https://insights.sbomify.com/CVE-2026-8134/): Concrete CMS Vulnerable to Relative Path Traversal (critical 9.4)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-81897 and fix it if it is affected.

What it is: CVE-2026-81897 is a high-severity cross-site scripting vulnerability in Concretecms Concrete Cms, published on 15 Sep 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-81897 in the wild and no public exploit code.

Affected product: Concretecms Concrete Cms. 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-2026-81897/ (Markdown: https://insights.sbomify.com/CVE-2026-81897/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-81897
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-81897
- OSV: https://osv.dev/vulnerability/CVE-2026-81897

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-81897/
Summaries are generated and may contain mistakes; the official description above is the record.