{"answers":{"affected":"It affects 1 product.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33020 exists.","fix":"Upgrade to a fixed version.","what":"CVE-2026-33020 is a high-severity vulnerability in saitoha libsixel, published on 14 Apr 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link."},"fix_prompt":"Check this codebase for CVE-2026-33020 and fix it if it is affected.\n\nWhat it is: CVE-2026-33020 is a high-severity vulnerability in saitoha libsixel, published on 14 Apr 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33020 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-2026-33020/ (Markdown: https://insights.sbomify.com/CVE-2026-33020/index.md)","id":"CVE-2026-33020","markdown":"https://insights.sbomify.com/CVE-2026-33020/index.md","name":"CVE-2026-33020","record":{"aliases":["DEBIAN-CVE-2026-33020","GHSA-2xgm-4x47-2x2p","UBUNTU-CVE-2026-33020"],"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 image library","requires_auth":"none","summary":"An integer overflow in libsixel allows attackers to cause heap corruption and potential code execution via crafted images.","user_interaction":"required","vuln_class":"integer_overflow"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"libsixel","vendor":"saitoha"}],"cvss":{"score":7.1,"severity":"high","source":"cna","vector":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H","version":"3.1"},"cwes":[{"id":"CWE-190","name":"Integer Overflow or Wraparound"},{"id":"CWE-122","name":"Heap-based Buffer Overflow"}],"description":"libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain an integer overflow which leads to a heap buffer overflow via sixel_frame_convert_to_rgb888() in frame.c, where allocation size and pointer offset computations for palettised images (PAL1, PAL2, PAL4) are performed using int arithmetic before casting to size_t. For images whose pixel count exceeds INT_MAX / 4, the overflow produces an undersized heap allocation for the conversion buffer and a negative pointer offset for the normalization sub-buffer, after which sixel_helper_normalize_pixelformat() writes the full image data starting from the invalid pointer, causing massive heap corruption confirmed by ASAN. An attacker providing a specially crafted large palettised PNG can corrupt the heap of the victim process, resulting in a reliable crash and potential arbitrary code execution.\nThis 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: Integer Overflow in write_png_to_file() leads to Heap-based Buffer Overflow","id":"CVE-2026-33020","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":null,"products":[],"type":"integer_overflow","year":"2026"},"n_packages":0,"n_references":2,"next":{"headline":"libsixel: Use-after-free in sixel_encoder_encode_bytes()","id":"CVE-2026-33021"},"packages":[],"prev":{"headline":"libsixel: Integer overflow leads to Out-of-bounds Read in img2sixel","id":"CVE-2026-33019"},"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":"total"},"state":"PUBLISHED","updated":"2026-04-15","vendors":["saitoha"]},"summary":"An integer overflow in libsixel allows attackers to cause heap corruption and potential code execution via crafted images.","url":"https://insights.sbomify.com/CVE-2026-33020/"}