# CVE-2026-18929: Resource Exhaustion in Carbone

> Attackers can crash the application server by submitting malicious .docx files containing zip bombs, causing excessive memory consumption.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L`)
- **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:** 18 Aug 2026
- **Updated:** 18 Aug 2026
- **Also known as:** GHSA-g3fg-g325-xmh2

## What is CVE-2026-18929?

CVE-2026-18929 is a medium-severity denial of service vulnerability in Carbone, published on 18 Aug 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

Carbone is vulnerable to Denial of Service due to lack of protection against zip bombs when processing .docx files. The library uses yazl for zip decompression without validating entry sizes, allowing an attacker to supply a malicious .docx file containing a zip bomb that decompresses to a significantly larger size, causing excessive memory consumption and crashing the application server.

The issue was fixed in versions: 3.8.2, 4.26.3 and 5.4.4.  The fix is available across all distribution types.

Weakness: CWE-409 (Improper Handling of Highly Compressed Data (Data Amplification))

## Which versions are affected by CVE-2026-18929?


## How do I fix CVE-2026-18929?

No fix has been published for CVE-2026-18929 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-18929 being exploited?

There is no known exploitation of CVE-2026-18929 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-18929 and fix it if it is affected.

What it is: CVE-2026-18929 is a medium-severity denial of service vulnerability in Carbone, published on 18 Aug 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-2026-18929 in the wild and no public exploit code.

Affected product: Carbone. 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-2026-18929/ (Markdown: https://insights.sbomify.com/CVE-2026-18929/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-18929
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-18929
- OSV: https://osv.dev/vulnerability/CVE-2026-18929

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-18929/
Summaries are generated and may contain mistakes; the official description above is the record.