high CVSS 8.2

CVE-2026-42591·Docker vulnerability

Gotenberg is a Docker-powered stateless API for PDF files. Prior to 8.32.0, 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 vulnerability is fixed in 8.32.0.

Severity
high
Software
Docker
Fixed in
8.32.0
Published
2026-05-14

Affected versions

Until: 8.32.0

Fixed in: 8.32.0

How to fix this CVE

Update Docker to the latest version that includes the patched Gotenberg component (8.32.0 or later). This vulnerability allows LibreOffice conversion requests to bypass SSRF protections by fetching external URLs embedded in documents. Immediately patch your Docker installation and review any document conversion workflows that accept user-supplied files.

sudo dnf update docker-ce

Defensia detects this vulnerability

What an exploitation attempt looks like

Sample log line indicative of exploitation attempts:

POST /forms/libreoffice/convert HTTP/1.1|multipart/form-data.*\.(doc|docx|xls|xlsx|ppt|pptx|odt)

WAF mitigation (if patching is not yet possible)

Add this rule to your WAF to block exploitation attempts while you schedule the patch. 

Implement strict input validation on document upload endpoints; reject files containing embedded external URLs or object linking references. Monitor all requests to /forms/libreoffice/convert and restrict this endpoint to trusted internal networks only. Consider implementing request size limits and file type whitelisting at the WAF level.

How to check if you are affected

  1. Step 1: Check installed Docker version with `docker --version` and compare against the fixed version 8.32.0
  2. Step 2: Verify if Gotenberg is running in your Docker environment with `docker ps | grep gotenberg` or check `docker images | grep gotenberg`
  3. Step 3: Search Docker and application logs for requests to the `/forms/libreoffice/convert` endpoint using `grep -r 'libreoffice/convert' /var/log/ --include='*.log'`
  4. Step 4: Confirm the patch by inspecting the running Gotenberg container image hash with `docker inspect <container_id> | grep Image` and cross-reference with the patched version in your Docker registry

FAQ

What is CVE-2026-42591?

This vulnerability affects Gotenberg's LibreOffice document conversion service running in Docker. The `/forms/libreoffice/convert` endpoint does not validate document content before passing it to LibreOffice, allowing attackers to embed external URLs that LibreOffice will fetch, bypassing intended SSRF protections.

Is CVE-2026-42591 being actively exploited?

There is no evidence of active exploitation in the wild, and no public exploits are currently available. However, the CVSS 8.2 score indicates high severity and organizations should prioritize patching.

What versions of Docker are affected by CVE-2026-42591?

All versions of Docker shipping Gotenberg prior to version 8.32.0 are affected. The vulnerability exists in any Gotenberg deployment running versions below 8.32.0.

How do I check if my server is vulnerable to CVE-2026-42591?

Run `docker images | grep gotenberg` to identify if Gotenberg is in use, then check the image tag or inspect the container with `docker inspect <container_id>` to determine the version number. Compare against 8.32.0.

Does Defensia detect CVE-2026-42591?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Docker with Gotenberg is installed on a monitored server, CVE-2026-42591 will appear in your dashboard with remediation steps.

Related Docker CVEs

CVE-2026-40281CVSS 10Gotenberg is a Docker-powered stateless API for PDF files. In versions 8.30.1 and earlier, the metadata write endpoint validates metadata keys for control characters but leaves metadata values unsanitized. A newline character in a metadata value splits the ExifTool stdin line into two separate arguments, allowing injection of arbitrary ExifTool pseudo-tags such as -FileName, -Directory, -SymLink, and -HardLink. This is a bypass of the incomplete key-sanitization fix introduced in v8.30.1. An unauthenticated attacker can rename or move any PDF being processed to an arbitrary path in the container filesystem, overwrite arbitrary files, or create symlinks and hard links at arbitrary paths.
CVE-2026-53576CVSS 10Kestra is an open-source, event-driven orchestration platform. Prior to 1.0.45 and 1.3.21, the authentication filter for the REST API (@Filter("/api/v1/**")) treats any request whose path ends in /configs as the public instance-config endpoint and forwards it without a credential check. kestra addresses its resources by URL path segments that the caller chooses (/api/v1/{tenant}/flows/{namespace}, /api/v1/{tenant}/executions/{namespace}/{id}, /api/v1/{tenant}/namespaces/{namespace}/kv/{key}). An anonymous caller picks the literal configs as the final segment, and the request bypasses Basic-Auth entirely. Because the bypass reaches the flow-create and execution-trigger routes, an unauthenticated caller creates a flow containing a Shell or Process task and runs it. The task executes as root inside the kestra container. The official docker-compose.yml mounts /var/run/docker.sock, so root in the container reaches the host Docker daemon. This vulnerability is fixed in 1.0.45 and 1.3.21.
CVE-2026-26216CVSS 10Crawl4AI versions prior to 0.8.0 contain a remote code execution vulnerability in the Docker API deployment. The /crawl endpoint accepts a hooks parameter containing Python code that is executed using exec(). The __import__ builtin was included in the allowed builtins, allowing unauthenticated remote attackers to import arbitrary modules and execute system commands. Successful exploitation allows full server compromise, including arbitrary command execution, file read and write access, sensitive data exfiltration, and lateral movement within internal networks.
CVE-2026-44329CVSS 10free5GC is an open-source implementation of the 5G core network. Prior to 4.2.2, free5GC's SMF mounts the UPI management route group without OAuth2/bearer-token authorization middleware. A network attacker who can reach SMF on the SBI can hit UPI endpoints with no Authorization header at all, and the requests reach the SMF business handlers. In the running Docker lab this was directly demonstrated for read (GET /upi/v1/upNodesLinks), write (POST /upi/v1/upNodesLinks with attacker-controlled UP-node and link payload), and delete (DELETE /upi/v1/upNodesLinks/{nodeID}) operations. This vulnerability is fixed in 4.2.2.
CVE-2026-33587CVSS 10Lack of user input sanitisation in Open Notebook v1.8.3 allows the application user to execute Python code (and subsequently OS commands) on the docker container via Server-Side Template Injection (SSTI) for user-created transformations.

References

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