CVE-2026-33021

{"id": "CVE-2026-33021", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.3, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H", "integrityImpact": "LOW", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "LOW"}, "impactScore": 4.7, "exploitabilityScore": 2.5}]}, "published": "2026-04-14T23:16:27.660", "references": [{"url": "https://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1", "tags": ["Release Notes"], "source": "security-advisories@github.com"}, {"url": "https://github.com/saitoha/libsixel/security/advisories/GHSA-j6m5-2cc7-3whc", "tags": ["Exploit", "Vendor Advisory"], "source": "security-advisories@github.com"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "security-advisories@github.com", "description": [{"lang": "en", "value": "CWE-416"}]}], "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."}], "lastModified": "2026-04-23T14:23:26.220", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:saitoha:libsixel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "E16EAA6A-544F-4D16-829D-1B7C9979EA6A", "versionEndExcluding": "1.8.7-r1"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}