{"cve":"CVE-2026-44636","nvd":{"published":"2026-05-14T20:17:08.703","modified":"2026-10-26T14:10:00.130","status":"Modified","description":"libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From  to 1.8.7-r1, signed integer overflow in sixel_encode_highcolor's allocation size calculation can lead to a heap buffer overflow. The public sixel_encode entry point validates only that width and height are greater than zero, with no upper bound. width and height are multiplied as plain int when computing the allocation size for paletted_pixels and normalized_pixels. Any caller that asks libsixel to encode a pixel buffer with width times height greater than INT_MAX (about 2.15 billion) will hit a wrapped allocation size; under the right wrap, the malloc succeeds with a buffer much smaller than the encoder expects, and the encoder writes past the end of the heap allocation. This vulnerability is fixed in 1.8.7-r2.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":["CWE-122","CWE-190"],"references":["https://github.com/saitoha/libsixel/security/advisories/GHSA-hx93-w8p2-ffh5","https://github.com/saitoha/libsixel/security/advisories/GHSA-hx93-w8p2-ffh5"],"products":["saitoha:libsixel"],"source":"nvd","synced_at":"2026-10-26T14:27:29.784594657+00:00"},"epss":{"cve":"CVE-2026-44636","score":0.00104,"percentile":0.00998,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}