CVE-2026-55241Public exploitNetwork attack vector

Pre-auth backend crash via unbounded upload buffering

Published Aug 21, 2026 · Updated Aug 25, 2026

Denial of service in BlueWave Labs Checkmate before 3.9.1 allows remote attackers to crash the backend via oversized profile uploads. The public registration route invokes in-memory Multer parsing before registration or invite validation, with no file-size, file-count, or MIME-type limits. Internet-reachable instances buffer concurrent multipart files before rejecting invalid requests, allowing memory exhaustion, an out-of-memory kill, or a backend crash.

CVSS severity7.5
High
EPSS probability0.44%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in BlueWave Labs Checkmate before 3.9.1 allows remote attackers to crash the backend via oversized profile uploads. The public registration route invokes in-memory Multer parsing before registration or invite validation, with no file-size, file-count, or MIME-type limits. Internet-reachable instances buffer concurrent multipart files before rejecting invalid requests, allowing memory exhaustion, an out-of-memory kill, or a backend crash.

The record

CVE
CVE-2026-55241
Published
Aug 21, 2026
Updated
Aug 25, 2026
Vendor
BlueWave Labs
Product
Checkmate
Classifications
CWE-770, CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 21, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 3.9.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

BlueWave Labs · Checkmateversion=< 3.9.1

Published CVSS scores

7.5GitHub Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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