libsixel: integer overflow in parser_CVE-2026-44637

{
    "lastseen": "",
    "description": "libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. From  to 1.8.7-r1, a signed integer overflow in the SIXEL parser's image-buffer doubling loop can lead to an out-of-bounds heap write in sixel_decode_raw_impl. context->pos_x grows by repeat_count on every sixel character with no upper bound check. Once pos_x approaches INT_MAX, the expression \"pos_x + repeat_count\" used to size the image buffer overflows signed int. Depending on how the overflow wraps, the resize check that should reject oversized buffers can be bypassed, after which a subsequent write computes a large attacker-influenced offset into image->data and writes past the allocation. Reachable from any caller that decodes attacker-supplied SIXEL data, including img2sixel. This vulnerability is fixed in 1.8.7-r2.",
    "published": "2026-05-14T20:02:32.034Z",
    "modified": "2026-05-14T20:02:32.034Z",
    "type": "cve",
    "title": "libsixel: integer overflow in parser",
    "source": "GitHub_M",
    "references": "https://github.com/saitoha/libsixel/security/advisories/GHSA-9jm7-77gr-qghv",
    "id": "CVE-2026-44637",
    "bulletinFamily": "",
    "cwe": [
        "CWE-190",
        "CWE-787"
    ],
    "cvelist": null,
    "sourceData": "saitoha libsixel >= 0.11.0, < 1.8.7-r2",
    "sourceHref": "",
    "cvss": {
        "score": 7.1,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
        "version": "",
        "vectorString": "",
        "baseScore": 0,
        "baseSeverity": "",
        "attackVector": "",
        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
            "vectorString": "",
            "baseScore": 0,
            "baseSeverity": "",
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        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "libsixel",
    "version": ">= 0.11.0, < 1.8.7-r2",
    "vendor": "saitoha",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}