TI-2026-47724 Aliases CVE-2026-67446 GHSA-75mr-qw9x-3r39

Mailpit: Thumbnail generation decodes unbounded image dimensions before scaling

MEDIUM 63CWE-400Published 2026-08-20 · Updated 2026-08-21

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · Low
Fix status: Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and GitHub. Impact type from CWE-400.

Summary

Mailpit is an email testing tool and API for developers. Prior to 1.30.4, Mailpit decodes attacker-supplied image attachments into a full raster before checking decoded dimensions, pixel count, or memory use in the GET /api/v1/message/{id}/part/{partID}/thumb endpoint. The Thumbnail handler in server/apiv1/thumbnails.go obtains attachment bytes through storage.GetAttachmentPart(), accepts image/* content, and calls imaging.Decode() with AutoOrientation before imaging.Fill() scales the image to 180 by 120 pixels. A compact image declaring very large dimensions can therefore consume disproportionately large memory and CPU, and opening the message UI can trigger the same endpoint through server/ui-src/components/message/MessageAttachments.vue. This can degrade availability when an unauthenticated client can store the crafted attachment and reach the web API. This issue is fixed in version 1.30.4.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00507 43rd percentileScored 2026-11-07

Fix Fixed mailpit (axllent): 1.30.4github.com/axllent/mailpit (Go): 1.30.4

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
axllent	mailpit	before 1.30.4	1.30.4	Patch available	CNA
—	github.com/axllent/mailpit (Go)	before 1.30.4	1.30.4	Patch available	GHSA-75mr-qw9x-3r39

mailpit Vendoraxllent Affected before 1.30.4 Fixed in 1.30.4 Patch available CNA
github.com/axllent/mailpit (Go) Vendor— Affected before 1.30.4 Fixed in 1.30.4 Patch available GHSA-75mr-qw9x-3r39

CPE names Threatist (inferred) · 1

Inferred from how NVD named this product before; not given by a source.

CPE	Versions	Role	Vendor
cpe:2.3:a:axllent:mailpit::::::::	—	—	axllent

cpe:2.3:a:axllent:mailpit:*:*:*:*:*:*:*:* Versions — — ·axllent

Remediation

Fix · CNA mailpit (axllent) Fixed in 1.30.4
Fix · GHSA-75mr-qw9x-3r39 github.com/axllent/mailpit (Go) Fixed in 1.30.4 Advisory →

Timeline

2026-10-02 Threatist record created from CVE-2026-67446
2026-10-03 Alias added: GHSA-75mr-qw9x-3r39

References

Advisory 1

https://nvd.nist.gov/vuln/detail/CVE-2026-67446

Other 4

TI-2026-22161 Mailpit is Vulnerable to Server-Side Request Forgery (SSRF) via Link Check API CVSS 3.1HIGH 8.6
TI-2026-33452 Mailpit: Unauthenticated remote memory-exhaustion DoS via unlimited SMTP DATA and /api/v1/send body sizes CVSS 3.1HIGH 7.5
TI-2026-33450 Mailpit: Path traversal & arbitrary file write in mailpit dump --http via attacker-controlled message IDs CVSS 3.1HIGH 8.2
TI-2026-39868 Mailpit: Incomplete SSRF protection in Link Check API via IPv6 transition mechanisms (follow-up to CVE-2026-27808) CVSS 3.1MEDIUM 5.8
TI-2026-17561 Mailpit Proxy Endpoint is Vulnerable to Server-Side Request Forgery (SSRF) CVSS 3.1MEDIUM 5.8
TI-2026-47725 Mailpit: SMTP DATA line reader buffers over-limit input before size enforcement CVSS 3.1MEDIUM 5.3

See all 15 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences