{"id":"CVE-2026-67446","state":"PUBLISHED","title":"Mailpit: Thumbnail generation decodes unbounded image dimensions before scaling","description":"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.","publishedAt":"2026-08-20T21:10:28.074Z","updatedAt":"2026-08-21T14:56:09.415Z","severity":{"score":5.3,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","source":"GitHub_M"},"assigner":"GitHub_M","products":["axllent mailpit"],"affected":[{"vendor":"axllent","product":"mailpit","versions":[{"version":"< 1.30.4","status":"affected"}]}],"references":["https://github.com/axllent/mailpit/security/advisories/GHSA-75mr-qw9x-3r39","https://github.com/axllent/mailpit/commit/6bcb6337838b542d53c348e38c7977f569b6db35","https://github.com/axllent/mailpit/releases/tag/v1.30.4"],"weaknesses":["CWE-400","CWE-770"],"ingestedAt":"2026-10-29T20:12:41.951Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/67xxx/CVE-2026-67446.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-67446","state":"PUBLISHED","datePublished":"2026-08-20T21:10:28.074Z","dateUpdated":"2026-08-21T14:56:09.415Z","assignerShortName":"GitHub_M","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateReserved":"2026-07-29T15:07:24.992Z"},"containers":{"cna":{"title":"Mailpit: Thumbnail generation decodes unbounded image dimensions before scaling","descriptions":[{"lang":"en","value":"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."}],"affected":[{"vendor":"axllent","product":"mailpit","versions":[{"version":"< 1.30.4","status":"affected"}]}],"references":[{"url":"https://github.com/axllent/mailpit/security/advisories/GHSA-75mr-qw9x-3r39","name":"https://github.com/axllent/mailpit/security/advisories/GHSA-75mr-qw9x-3r39","tags":["x_refsource_CONFIRM"]},{"url":"https://github.com/axllent/mailpit/commit/6bcb6337838b542d53c348e38c7977f569b6db35","name":"https://github.com/axllent/mailpit/commit/6bcb6337838b542d53c348e38c7977f569b6db35","tags":["x_refsource_MISC"]},{"url":"https://github.com/axllent/mailpit/releases/tag/v1.30.4","name":"https://github.com/axllent/mailpit/releases/tag/v1.30.4","tags":["x_refsource_MISC"]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":5.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","version":"3.1"}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-400","lang":"en","description":"CWE-400: Uncontrolled Resource Consumption","type":"CWE"}]},{"descriptions":[{"cweId":"CWE-770","lang":"en","description":"CWE-770: Allocation of Resources Without Limits or Throttling","type":"CWE"}]}],"providerMetadata":{"shortName":"GitHub_M","orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","dateUpdated":"2026-08-20T21:10:28.074Z"},"source":{"advisory":"GHSA-75mr-qw9x-3r39","discovery":"UNKNOWN"}},"adp":[{"title":"CISA ADP Vulnrichment","references":[{"url":"https://github.com/axllent/mailpit/security/advisories/GHSA-75mr-qw9x-3r39","tags":["exploit"]}],"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-08-21T14:56:02.744495Z","id":"CVE-2026-67446","options":[{"Exploitation":"poc"},{"Automatable":"yes"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-08-21T14:56:09.415Z"}}]}}}