# CVE-2026-61453: Grav before 2.0.1 XSS via Twig String Concatenation

> Attackers with page-write permissions can execute arbitrary JavaScript in visitors' browsers by bypassing XSS validation via Twig string concatenation.

- **Severity:** Medium 5.1 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/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:** Yes
- **Published:** 15 Jul 2026
- **Updated:** 8 Oct 2026
- **Also known as:** CVE-2026-61710, GHSA-2c4f-86xc-cr74

## What is CVE-2026-61453?

CVE-2026-61453 is a medium-severity cross-site scripting vulnerability in getgrav grav, published on 15 Jul 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

Grav v2.0.0 contains a cross-site scripting vulnerability (fixed in 2.0.1). The XSS blueprint validator (Security::detectXss()) runs on raw page content before Twig processing. When Twig content processing is enabled (twig_content.process_enabled: true), an attacker with page-write API permission can use Twig's string concatenation operator (~) to dynamically construct event handler names, dangerous tag names, or dangerous protocols at render time (e.g. {% set x = "on" ~ "error" %}). The validator sees only the harmless Twig expression and allows the content, but after Twig rendering the output (rendered via {{ page.content|raw }}) contains an active payload such as <img src=1 onerror=alert(1)>, executing arbitrary JavaScript in visitors' browsers.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-61453?

2 open source packages ship an affected version, including getgrav/grav.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `getgrav/grav` | Packagist | From 2.0.0 | 2.0.1 |
| `getgrav/grav` | Packagist | From 2.0.0 | 2.0.1 |

## How do I fix CVE-2026-61453?

Upgrade getgrav/grav to 2.0.1 or later.

## Is CVE-2026-61453 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-61453 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-61453 and fix it if it is affected.

What it is: CVE-2026-61453 is a medium-severity cross-site scripting vulnerability in getgrav grav, published on 15 Jul 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-61453 exists.

Affected packages and fixed versions:
- getgrav/grav (Packagist): affected from 2.0.0; fixed in 2.0.1
- getgrav/grav (Packagist): affected from 2.0.0; fixed in 2.0.1

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-2026-61453/ (Markdown: https://insights.sbomify.com/CVE-2026-61453/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-61453
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-61453
- OSV: https://osv.dev/vulnerability/CVE-2026-61453

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-61453/
Summaries are generated and may contain mistakes; the official description above is the record.