Vanden Broele eSignFlow · Breach

Hacker obtains national ID numbers of Belgian eSignFlow signers

Oct 27, 2026 · 1 min read

A hacker obtained the national ID numbers of people who signed documents on eSignFlow, the e-signature tool used by 120+ Belgian councils. Maker Vanden Broele says the hashed numbers are easy to reverse and some handwritten signatures leaked too; its CEO said mostly metadata leaked. No fix is cited; organizations using the tool should assess signer data exposure.

By HIFY Radar newsroom Updated 10/27/2026 05:56 PM Get this every day →← Back to the feed 1 source

MediumBreachNo software to update

In this article

What happened
Why it matters
What to do
For the technical team
Timeline
Sources

What happened

A hacker obtained the national ID numbers of people who signed documents on eSignFlow, an e-signature tool used by 120+ Belgian councils. Maker Vanden Broele says the hashed numbers are easy to reverse. Some handwritten signatures leaked too.

Why it matters

Data on citizens who signed documents through this tool may be exposed, including national ID numbers. Vanden Broele's CEO said mostly metadata leaked. More than 120 Belgian councils use the tool, so public bodies are accountable for signer data.

What to do

Check whether the organization uses eSignFlow and identify which documents and signer data may be involved. Follow Vanden Broele's communications on the case.

For the technical team

Affected: Vanden Broele eSignFlow, ferramenta de assinatura eletrônica usada por mais de 120 conselhos municipais belgas · Vanden Broele eSignFlow, an e-signature tool used by 120+ Belgian councils. Versions not cited in the source.
Exploitation: Data acquisition reported by IntCyberDigest. No mention in the source of PoC, active vulnerability exploitation, or KEV.
Fix: The source mentions no fix, patch, or mitigation.
Vector: Data leak in the eSignFlow e-signature tool. The source does not describe how the hacker obtained the data. National ID numbers were stored hashed, but Vanden Broele admits they are easy to reverse.
More details: Vanden Broele acknowledges the hashes are reversible and that some handwritten signatures leaked. On Monday, the company's CEO said mostly metadata leaked. The source names no hacker, group, method, or leak date.