CVE-2026-67446Public exploitNetwork attack vectorHinoki check available

Service interrupt via oversized thumbnail decode

Published Aug 20, 2026 · Updated Aug 20, 2026

Resource exhaustion in the thumbnail endpoint in Axllent Mailpit before 1.30.4 allows remote attackers to cause a service interrupt via crafted image attachments. The GET /api/v1/message/{id}/part/{partID}/thumb handler in server/apiv1/thumbnails.go reparses stored attachment bytes and calls imaging.Decode() on image/* content before checking declared dimensions or decoded pixel count, so a small compressed image can expand into a large in-memory raster before imaging.Fill() scales it to 180x120. Exposure requires a deployment where remote attackers can store a message and reach the web API; opening the affected message in the UI can trigger the same decode path through MessageAttachments.vue.

CVSS severity5.3
Medium
EPSS probability0.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Resource exhaustion in the thumbnail endpoint in Axllent Mailpit before 1.30.4 allows remote attackers to cause a service interrupt via crafted image attachments. The GET /api/v1/message/{id}/part/{partID}/thumb handler in server/apiv1/thumbnails.go reparses stored attachment bytes and calls imaging.Decode() on image/* content before checking declared dimensions or decoded pixel count, so a small compressed image can expand into a large in-memory raster before imaging.Fill() scales it to 180x120. Exposure requires a deployment where remote attackers can store a message and reach the web API; opening the affected message in the UI can trigger the same decode path through MessageAttachments.vue.

The record

CVE
CVE-2026-67446
Published
Aug 20, 2026
Updated
Aug 20, 2026
Vendor
Axllent
Product
Mailpit
Classifications
CWE-770, CWE-400, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 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=< 1.30.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Axllent · Mailpitversion=< 1.30.4

Published CVSS scores

5.3GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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
T1499.003Application Exhaustion Flood

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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