libsixel: Integer overflow leads to Out-of-bounds Read in img2sixel_CVE-2026-33019

{
    "lastseen": "",
    "description": "libsixel is a SIXEL encoder/decoder implementation derived from kmiya's sixel. Versions 1.8.7 and prior contain an integer overflow leading to an out-of-bounds heap read in the --crop option handling of img2sixel, where positive coordinates up to INT_MAX are accepted without overflow-safe bounds checking. In sixel_encoder_do_clip(), the expression clip_w + clip_x overflows to a large negative value when clip_x is INT_MAX, causing the bounds guard to be skipped entirely, and the unclamped coordinate is passed through sixel_frame_clip() to clip(), which computes a source pointer far beyond the image buffer and passes it to memmove(). An attacker supplying a specially crafted crop argument with any valid image can trigger an out-of-bounds read in the heap, resulting in a reliable crash and potential information disclosure. This issue has been fixed in version 1.8.7-r1.",
    "published": "2026-04-14T21:49:25.204Z",
    "modified": "2026-04-14T21:49:25.204Z",
    "type": "cve",
    "title": "libsixel: Integer overflow leads to Out-of-bounds Read in img2sixel",
    "source": "GitHub_M",
    "references": "https://github.com/saitoha/libsixel/security/advisories/GHSA-c854-ffg9-g72c\nhttps://github.com/saitoha/libsixel/releases/tag/v1.8.7-r1",
    "id": "CVE-2026-33019",
    "bulletinFamily": "",
    "cwe": [
        "CWE-125",
        "CWE-190"
    ],
    "cvelist": null,
    "sourceData": "saitoha libsixel < 1.8.7-r1",
    "sourceHref": "",
    "cvss": {
        "score": 7.1,
        "severity": "HIGH",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/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": "",
            "attackVector": "",
            "attackComplexity": "",
            "privilegesRequired": "",
            "userInteraction": "",
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            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "libsixel",
    "version": "< 1.8.7-r1",
    "vendor": "saitoha",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}