# CVE-2026-123824: Symfony: XXE (Local File Read) in Config XmlUtils::parse() via validateOnParse = true


- **Severity:** Low 2.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 6 Nov 2026
- **Updated:** 6 Nov 2026
- **Also known as:** DEBIAN-CVE-2026-123824, GHSA-5jff-8h8q-r5qx, UBUNTU-CVE-2026-123824

## What is CVE-2026-123824?

CVE-2026-123824 is a low-severity vulnerability in sensiolabs symfony, published on 6 Nov 2026. 

### Official description

The Symfony Config component XmlUtils::parse() enables DTD validation before rejecting documents that carry a doctype, allowing XML external entity (XXE) injection in Symfony versions prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11. A remote attacker who can supply XML to this method can determine whether local files exist, cause a denial of service, and, in some configurations, exfiltrate local file content via a crafted XML document whose doctype declares an external file:// entity.
XmlUtils::parse() sets $dom->validateOnParse = true before calling loadXML() and only rejects documents carrying a doctype afterwards. Enabling DTD validation makes libxml resolve external entities during loadXML(), and LIBXML_NONET blocks http:// but not file://, so a file:// entity is read from disk before the doctype rejection runs. The content of the file is not returned to the caller, but the distinct libxml error for a missing path reveals whether a file exists, and an entity pointing at a large or slow file causes a denial of service. If the application registers a network-capable stream wrapper such as s3://, a parameter entity can also send the content of a local file to an external server. This is the same issue as CVE-2026-45071, which was fixed in the DomCrawler component but not in Config.

Applications are affected if they pass untrusted XML to XmlUtils::parse() directly. The Symfony components that call it process developer-provided or operator-configured sources, such as configuration files and the XLIFF documents fetched by the translation providers.

Weakness: CWE-611 (Improper Restriction of XML External Entity Reference)

## Which versions are affected by CVE-2026-123824?


## How do I fix CVE-2026-123824?

Upgrade to a fixed version.

## Is CVE-2026-123824 being exploited?

There is no known exploitation of CVE-2026-123824 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123824 and fix it if it is affected.

What it is: CVE-2026-123824 is a low-severity vulnerability in sensiolabs symfony, published on 6 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-123824 in the wild and no public exploit code.

Affected product: sensiolabs symfony. 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-2026-123824/ (Markdown: https://insights.sbomify.com/CVE-2026-123824/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123824
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123824
- OSV: https://osv.dev/vulnerability/CVE-2026-123824

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123824/
Summaries are generated and may contain mistakes; the official description above is the record.