{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-33021","assignerOrgId":"a0819718-46f1-4df5-94e2-005712e83aaa","state":"PUBLISHED","assignerShortName":"GitHub_M","dateReserved":"2026-03-17T17:22:14.667Z","datePublished":"2026-04-14T21:57:22.817Z","dateUpdated":"2026-04-16T13:54:36.177Z"},"containers":{"cna":{"title":"libsixel: Use-after-free in sixel_encoder_encode_bytes()","problemTypes":[{"descriptions":[{"cweId":"CWE-416","lang":"en","description":"CWE-416: Use After Free","type":"CWE"}]}],"metrics":[{"cvssV3_1":{"attackComplexity":"LOW","attackVector":"LOCAL","availabilityImpact":"HIGH","baseScore":7.3,"baseSeverity":"HIGH","confidentialityImpact":"LOW","integrityImpact":"LOW","privilegesRequired":"NONE","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H","version":"3.1"}}],"references":[{"name":"https://github.com/saitoha/libsixel/security/advisories/GHSA-j6m5-2cc7-3whc","tags":["x_refsource_CONFIRM"],"url":"https://github.com/saitoha/libsixel/security/advisories/GHSA-j6m5-2cc7-3whc"},{"name":"https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1","tags":["x_refsource_MISC"],"url":"https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1"}],"affected":[{"vendor":"saitoha","product":"libsixel","versions":[{"version":"< 1.8.7-r1","status":"affected"}]}],"providerMetadata":{"orgId":"a0819718-46f1-4df5-94e2-005712e83aaa","shortName":"GitHub_M","dateUpdated":"2026-04-14T21:57:22.817Z"},"descriptions":[{"lang":"en","value":"libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain a use-after-free vulnerability in sixel_encoder_encode_bytes() because sixel_frame_init() stores the caller-owned pixel buffer pointer directly in frame->pixels without making a defensive copy. When a resize operation is triggered, sixel_frame_convert_to_rgb888() unconditionally frees this caller-owned buffer and replaces it with a new internal allocation, leaving the caller with a dangling pointer. Any subsequent access to the original buffer by the caller constitutes a use-after-free, confirmed by AddressSanitizer. An attacker who controls incoming frames can trigger this bug repeatedly and predictably, resulting in a reliable crash with potential for code execution. This issue has been fixed in version 1.8.7-r1."}],"source":{"advisory":"GHSA-j6m5-2cc7-3whc","discovery":"UNKNOWN"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2026-04-16T13:54:16.495174Z","id":"CVE-2026-33021","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2026-04-16T13:54:36.177Z"}}]}}