{"answers":{"affected":"It affects 1 product.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33021 exists.","fix":"Upgrade to a fixed version.","what":"CVE-2026-33021 is a high-severity use after free vulnerability in saitoha libsixel, published on 14 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-33021 and fix it if it is affected.\n\nWhat it is: CVE-2026-33021 is a high-severity use after free vulnerability in saitoha libsixel, published on 14 Apr 2026. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33021 exists.\n\nAffected product: saitoha libsixel. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-33021/ (Markdown: https://insights.sbomify.com/CVE-2026-33021/index.md)","id":"CVE-2026-33021","markdown":"https://insights.sbomify.com/CVE-2026-33021/index.md","name":"CVE-2026-33021","record":{"aliases":["DEBIAN-CVE-2026-33021","GHSA-j6m5-2cc7-3whc","UBUNTU-CVE-2026-33021"],"analysis":{"component_type":"library","fix_type":"upgrade","impacts":["code_execution","denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"SIXEL encoder library","requires_auth":"none","summary":"An attacker can trigger a use-after-free in libsixel by controlling input frames, potentially leading to code execution or crashes.","user_interaction":"not_required","vuln_class":"use_after_free"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"libsixel","vendor":"saitoha"}],"cvss":{"score":7.3,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H","version":"3.1"},"cwes":[{"id":"CWE-416","name":"Use After Free"}],"description":"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-\u003epixels 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.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"weaponised"},"has_fix":true,"headline":"libsixel: Use-after-free in sixel_encoder_encode_bytes()","id":"CVE-2026-33021","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"use_after_free","year":"2026"},"n_packages":0,"n_references":2,"next":{"headline":"Tekton Pipelines: Controller can panic when setting long resolver names in TaskRun/PipelineRun","id":"CVE-2026-33022"},"packages":[],"prev":{"headline":"libsixel: Integer Overflow in write_png_to_file() leads to Heap-based Buffer Overflow","id":"CVE-2026-33020"},"products":["libsixel"],"published":"2026-04-14","related":[{"cvss_score":9.8,"headline":"Memory corruption in n/a","id":"CVE-2019-19635","kev_date_added":null,"published":"2019-12-08"},{"cvss_score":9.8,"headline":"Integer overflow in n/a","id":"CVE-2019-19636","kev_date_added":null,"published":"2019-12-08"},{"cvss_score":9.8,"headline":"Integer overflow in n/a","id":"CVE-2019-19637","kev_date_added":null,"published":"2019-12-08"},{"cvss_score":9.8,"headline":"Integer overflow in n/a","id":"CVE-2019-19638","kev_date_added":null,"published":"2019-12-08"},{"cvss_score":8.8,"headline":"Memory corruption in n/a","id":"CVE-2022-27044","kev_date_added":null,"published":"2022-04-08"},{"cvss_score":8.8,"headline":"Use after free in n/a","id":"CVE-2022-27046","kev_date_added":null,"published":"2022-04-08"},{"cvss_score":8.8,"headline":"Memory corruption in n/a","id":"CVE-2020-21547","kev_date_added":null,"published":"2021-09-17"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"poc","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-04-16","vendors":["saitoha"]},"summary":"An attacker can trigger a use-after-free in libsixel by controlling input frames, potentially leading to code execution or crashes.","url":"https://insights.sbomify.com/CVE-2026-33021/"}