CVE-2026-33023

{"id": "CVE-2026-33023", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-33023", "role": "CISA Coordinator", "options": [{"exploitation": "poc"}, {"automatable": "no"}, {"technicalImpact": "total"}], "version": "2.0.3", "timestamp": "2026-04-15T18:48:25.027963Z"}}], "cvssMetricV31": [{"type": "Secondary", "source": "security-advisories@github.com", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "NONE", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 1.8}]}, "affected": [{"source": "security-advisories@github.com", "affectedData": [{"vendor": "saitoha", "product": "libsixel", "versions": [{"status": "affected", "version": "< 1.8.7-r1"}]}]}], "published": "2026-04-14T23:16:27.820", "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-hr25-g2j6-qjw6", "tags": ["Exploit", "Vendor Advisory"], "source": "security-advisories@github.com"}, {"url": "https://github.com/saitoha/libsixel/security/advisories/GHSA-hr25-g2j6-qjw6", "tags": ["Exploit", "Vendor Advisory"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "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. In versions 1.8.7 and prior, when built with the --with-gdk-pixbuf2 option, a use-after-free vulnerability exists in load_with_gdkpixbuf() in loader.c. The cleanup path manually frees the sixel_frame_t object and its internal buffers without consulting the reference count, even though the object was created via the refcounted constructor sixel_frame_new() and exposed to the public callback. A callback that calls sixel_frame_ref(frame) to retain a logically valid reference will hold a dangling pointer after sixel_helper_load_image_file() returns, and any subsequent access to the frame or its fields triggers a use-after-free confirmed by AddressSanitizer. The root cause is a consistency failure between two cleanup strategies in the same codebase: sixel_frame_unref() is used in load_with_builtin() but raw free() is used in load_with_gdkpixbuf(). An attacker supplying a crafted image to any application built against libsixel with gdk-pixbuf2 support can trigger this reliably, potentially leading to information disclosure, memory corruption, or code execution. This issue has been fixed in version 1.8.7-r1."}, {"lang": "es", "value": "libsixel es una implementaci\u00f3n de codificador/decodificador SIXEL derivada del sixel de kmiya. En las versiones 1.8.7 y anteriores, cuando se compila con la opci\u00f3n --with-gdk-pixbuf2, existe una vulnerabilidad de uso despu\u00e9s de liberaci\u00f3n en load_with_gdkpixbuf() en loader.c. La ruta de limpieza libera manualmente el objeto sixel_frame_t y sus b\u00faferes internos sin consultar el recuento de referencias, a pesar de que el objeto fue creado a trav\u00e9s del constructor con recuento de referencias sixel_frame_new() y expuesto a la devoluci\u00f3n de llamada p\u00fablica. Una devoluci\u00f3n de llamada que llama a sixel_frame_ref(frame) para retener una referencia l\u00f3gicamente v\u00e1lida mantendr\u00e1 un puntero colgante despu\u00e9s de que sixel_helper_load_image_file() regrese, y cualquier acceso posterior al marco o sus campos activa un uso despu\u00e9s de liberaci\u00f3n confirmado por AddressSanitizer. La causa ra\u00edz es una falla de consistencia entre dos estrategias de limpieza en la misma base de c\u00f3digo: sixel_frame_unref() se usa en load_with_builtin() pero free() sin procesar se usa en load_with_gdkpixbuf(). Un atacante que suministre una imagen manipulada a cualquier aplicaci\u00f3n compilada contra libsixel con soporte para gdk-pixbuf2 puede activar esto de manera fiable, lo que podr\u00eda conducir a revelaci\u00f3n de informaci\u00f3n, corrupci\u00f3n de memoria o ejecuci\u00f3n de c\u00f3digo. Este problema ha sido solucionado en la versi\u00f3n 1.8.7-r1."}], "lastModified": "2026-07-25T11:10:00.100", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:saitoha:libsixel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "49AAE0F5-8747-4FA0-9E7F-37FC054A3198", "versionEndIncluding": "1.8.7"}], "operator": "OR"}]}], "sourceIdentifier": "security-advisories@github.com"}