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HighVulnerabilityCVE-2026-119036updated 30 Oct 2026, 17:22 UTC

Perl GoCardless webhook library can be crashed by oversized unsigned requests

A specially crafted web request sent to a webhook receiver can make the program run out of memory and stop working. The attacker does not need a valid signature for the request to cause this.

Fixed in Version 1.01 · out Official, 2 sources
SeverityHighVulnerability
Being exploited?UnclearNo reports either way yet
Fix available?YesVersion 1.01 · since 30 Oct 2026
How sure is this?Official, 2 sourcesBacked by an official source

How the attack works simplified

  1. 1AttackerSends one request with no valid signature
  2. 2Webhook endpointRequest reaches the receiving application
  3. 3Legacy verificationPayload flattened before signature check
  4. 4Memory growsKey length times array length adds up
  5. ResultReceiving process runs out of memory

What happened

Business::GoCardless for Perl, versions before 1.01, flattens legacy webhook payloads into key-value pairs before verifying the signature, so memory use grows with the product of key length and array length.

Why it is dangerous: A remote attacker can exhaust memory in the process receiving webhooks with one unsigned request, causing denial of service for payment webhook handling.

Are you affected?

You are affected if you run Business::GoCardless for Perl before version 1.01 and accept webhooks that contain a top-level "payload" key.

Business::GoCardless (Perl) versions before 1.01

What to do

  1. Update Business::GoCardless for Perl to version 1.01 or later
  2. Restart any service that receives GoCardless webhooks after updating
  3. Limit request body size at your web server or reverse proxy as an extra safeguard

Timeline

  1. 30 Oct 2026, 13:18 UTC
    Publicly disclosed
  2. 30 Oct 2026, 15:47 UTC
    Reported by oss-security · oss-security
  3. 30 Oct 2026, 16:00 UTC
    Picked up by Zero Radar
  4. 30 Oct 2026, 17:22 UTC
    NVD reported on it · NVD

Sources 2 reports, oldest first

Official vendor, government CERT or advisory database

Security researchers research teams and mailing lists

Technical details

ID
CVE-2026-119036
Disclosed
30 Oct 2026, 13:18 UTC
On Zero Radar
30 Oct 2026, 16:00 UTC (3 h after disclosure)
Last change
30 Oct 2026, 17:22 UTC

The plain-language parts and the attack diagram were written by an AI model (anthropic/claude-haiku-5.5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Perl GoCardless webhook library can be crashed by oversized unsigned requests · Zero Radar