osslsigncode has an Integer Underflow in PE Page Hash Calculation Can Cause Out-of-Bounds Read_CVE-2026-39855

{
    "lastseen": "",
    "description": "osslsigncode is a tool that implements Authenticode signing and timestamping. Prior to 2.13, an integer underflow vulnerability exists in osslsigncode version 2.12 and earlier in the PE page-hash computation code (pe_page_hash_calc()). When page hash processing is performed on a PE file, the function subtracts hdrsize from pagesize without first validating that pagesize >= hdrsize. If a malicious PE file sets SizeOfHeaders (hdrsize) larger than SectionAlignment (pagesize), the subtraction underflows and produces a very large unsigned length. The code allocates a zero-filled buffer of pagesize bytes and then attempts to hash pagesize - hdrsize bytes from that buffer. After the underflow, this results in an out-of-bounds read from the heap and can crash the process. The vulnerability can be triggered while signing a malicious PE file with page hashing enabled (-ph), or while verifying a malicious signed PE file that already contains page hashes. Verification of an already signed file does not require the verifier to pass -ph. This vulnerability is fixed in 2.13.",
    "published": "2026-04-09T15:58:38.559Z",
    "modified": "2026-04-09T19:22:16.659Z",
    "type": "cve",
    "title": "osslsigncode has an Integer Underflow in PE Page Hash Calculation Can Cause Out-of-Bounds Read",
    "source": "GitHub_M",
    "references": "https://github.com/mtrojnar/osslsigncode/security/advisories/GHSA-76vv-x5rr-q3mr\nhttps://github.com/mtrojnar/osslsigncode/commit/2a5409b7c4b6c6fad2b093531e8fea6cf08e1568\nhttps://github.com/mtrojnar/osslsigncode/releases/tag/2.13",
    "id": "CVE-2026-39855",
    "bulletinFamily": "",
    "cwe": [
        "CWE-125",
        "CWE-190",
        "CWE-191"
    ],
    "cvelist": null,
    "sourceData": "mtrojnar osslsigncode < 2.13",
    "sourceHref": "",
    "cvss": {
        "score": 5.5,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/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": "",
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            "confidentialityImpact": "",
            "integrityImpact": "",
            "availabilityImpact": ""
        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "osslsigncode",
    "version": "< 2.13",
    "vendor": "mtrojnar",
    "ai_description": "",
    "ai_severity": "",
    "ai_vendor": "",
    "ai_product": "",
    "ai_version": "",
    "ai_score": 0
}