{"description":"Trending threats, MITRE ATT\u0026CK coverage, and detection metadata — refreshed continuously.","feed_url":"https://feed.craftedsignal.io/tags/libsixel/","home_page_url":"https://feed.craftedsignal.io/","items":[{"_cs_actors":[],"_cs_cves":[{"cvss":7,"id":"CVE-2026-33018"}],"_cs_exploited":false,"_cs_products":[],"_cs_severities":["high"],"_cs_tags":["libsixel","use-after-free","CVE-2026-33018","gif"],"_cs_type":"advisory","_cs_vendors":[],"content_html":"\u003cp\u003eLibsixel, a SIXEL encoder/decoder implementation, is vulnerable to a use-after-free vulnerability (CVE-2026-33018) in versions 1.8.7 and prior. The flaw resides in the \u003ccode\u003eload_gif()\u003c/code\u003e function within \u003ccode\u003efromgif.c\u003c/code\u003e. The vulnerability stems from the reuse of a single \u003ccode\u003esixel_frame_t\u003c/code\u003e object across all frames of an animated GIF. The \u003ccode\u003egif_init_frame()\u003c/code\u003e function unconditionally frees and reallocates \u003ccode\u003eframe-\u0026gt;pixels\u003c/code\u003e between frames without checking the object\u0026rsquo;s reference count. This can lead to a dangling pointer if an application uses \u003ccode\u003esixel_helper_load_image_file()\u003c/code\u003e with a multi-frame callback and the documented usage pattern of \u003ccode\u003esixel_frame_ref()\u003c/code\u003e and \u003ccode\u003esixel_frame_get_pixels()\u003c/code\u003e, resulting in a heap use-after-free. Exploitation could result in a crash or, potentially, arbitrary code execution. This issue is resolved in version 1.8.7-r1.\u003c/p\u003e\n\u003ch2 id=\"attack-chain\"\u003eAttack Chain\u003c/h2\u003e\n\u003col\u003e\n\u003cli\u003eAn attacker crafts a malicious animated GIF file.\u003c/li\u003e\n\u003cli\u003eThe attacker delivers the malicious GIF to a vulnerable application using \u003ccode\u003elibsixel\u003c/code\u003e. This delivery mechanism could involve various means, such as embedding the image in a document, website, or email.\u003c/li\u003e\n\u003cli\u003eThe vulnerable application uses the \u003ccode\u003esixel_helper_load_image_file()\u003c/code\u003e function to load the crafted GIF.\u003c/li\u003e\n\u003cli\u003eThe \u003ccode\u003eload_gif()\u003c/code\u003e function within \u003ccode\u003efromgif.c\u003c/code\u003e processes the GIF frames.\u003c/li\u003e\n\u003cli\u003eDuring processing, the \u003ccode\u003egif_init_frame()\u003c/code\u003e function frees and reallocates the \u003ccode\u003eframe-\u0026gt;pixels\u003c/code\u003e buffer for each frame of the animated GIF without properly managing the object\u0026rsquo;s reference count.\u003c/li\u003e\n\u003cli\u003eA callback function, following the documented usage of \u003ccode\u003esixel_frame_ref()\u003c/code\u003e to retain a frame and \u003ccode\u003esixel_frame_get_pixels()\u003c/code\u003e to access the pixel data, now holds a dangling pointer to the previously freed memory.\u003c/li\u003e\n\u003cli\u003eWhen the callback function attempts to access the pixel data via the dangling pointer, a use-after-free condition occurs.\u003c/li\u003e\n\u003cli\u003eThis use-after-free can lead to a program crash or, potentially, allow the attacker to execute arbitrary code by manipulating the freed memory.\u003c/li\u003e\n\u003c/ol\u003e\n\u003ch2 id=\"impact\"\u003eImpact\u003c/h2\u003e\n\u003cp\u003eSuccessful exploitation of this vulnerability could lead to application crashes, denial of service, or potentially arbitrary code execution. The impact depends on the specific application using the vulnerable \u003ccode\u003elibsixel\u003c/code\u003e library. Applications that process user-supplied animated GIFs are particularly at risk. There is no publicly available information about specific victims or sectors targeted by this vulnerability.\u003c/p\u003e\n\u003ch2 id=\"recommendation\"\u003eRecommendation\u003c/h2\u003e\n\u003cul\u003e\n\u003cli\u003eUpgrade to libsixel version 1.8.7-r1 or later to patch CVE-2026-33018.\u003c/li\u003e\n\u003cli\u003eDeploy the Sigma rule to detect processes loading the vulnerable libsixel library and processing GIF files to detect exploitation attempts.\u003c/li\u003e\n\u003cli\u003eMonitor web server logs for requests containing potentially malicious GIF files being uploaded to the server to prevent initial access.\u003c/li\u003e\n\u003c/ul\u003e\n","date_modified":"2026-04-15T12:00:00Z","date_published":"2026-04-15T12:00:00Z","id":"/briefs/2026-04-libsixel-uaf/","summary":"A use-after-free vulnerability exists in libsixel versions 1.8.7 and prior when processing animated GIFs due to improper frame buffer management, potentially leading to code execution.","title":"Libsixel Use-After-Free Vulnerability (CVE-2026-33018)","url":"https://feed.craftedsignal.io/briefs/2026-04-libsixel-uaf/"}],"language":"en","title":"CraftedSignal Threat Feed — Libsixel","version":"https://jsonfeed.org/version/1.1"}