GCVE-1988-2026-0186
Vulnerability from gna-1988 – Published: 2026-09-08 07:57 – Updated: 2026-09-08 07:57
VLAI
EPSS
VEX
Title
Blind XXE in Electronic Invoice online tools (validator.invoice-portal.de, xrechnung.rib.de)
Summary
During tests of electronic invoicing tools, I discovered multiple XXE
and Blind XXE vulnerabilities in online tools parsing electronic
invoices in XML formats.
While most of the affected tools have fixed these vulnerabilities, two
online tools remain vulnerable to Blind XXE attacks, allowing
exfiltration of files. Disclosure to the affected operators happened
more than 90 days ago.
Vulnerable tools:
https://validator.invoice-portal.de/
https://xrechnung.rib.de/ (only the visualization tool)
In both cases, uploading an invoice with a blind XXE payload leads to
HTTP requests to the attacker's server and exfiltrates file content.
Proof of concepts, e.g., to exfiltrate /etc/hostname
(ciibxxehostname.xml), can be found here:
https://github.com/hannob/invoicesec
Timeline validator.invoice-portal.de:
2025-11-17 Informed support contact about Blind XXE vulnerability, no
reply
2026-02-16 Still vulnerable, public disclosure
Timeline xrechnung.rib.de:
2025-10-29 Reported "standard" XXE via contact form, no reply
2025-11-18 Re-test, incomplete fix: "Standard" XXE fixed, Blind XXE
still possible
2025-11-18 Re-reported incomplete fix, no reply
2026-02-16 Still vulnerable, public disclosure
This was part of a larger research effort about the security of EU
electronic invoices:
https://invoice.secvuln.info/
--
Hanno Böck - Independent security researcher
https://itsec.hboeck.de/
https://badkeys.info/
_______________________________________________
Sent through the Full Disclosure mailing list
https://nmap.org/mailman/listinfo/fulldisclosure
Web Archives & RSS: https://seclists.org/fulldisclosure/
Severity
No CVSS data available.
Assigner
References
10 references
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| unknown | Blind XXE in |
Affected:
unknown
|
guessed |
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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