GHSA-GPR4-C479-XRW4
Vulnerability from github – Published: 2026-10-02 09:31 – Updated: 2026-10-02 09:31Memory allocation with excessive size value in the HSS/LMS signature code (HssPublicKeyParameters, HssSignature) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote unauthenticated attacker who can supply both an HSS public key and a signature to cause a denial of service through memory exhaustion via a public key encoding with an excessive level count, because the level count L read when parsing an HSS public key was not checked against the RFC 8554 maximum of 8, and signature parsing then allocated an array of L - 1 entries before reading any further signature data. A single verification can commit up to about 17 GB of memory or fail with an OutOfMemoryException.
{
"affected": [],
"aliases": [
"CVE-2026-103603"
],
"database_specific": {
"cwe_ids": [
"CWE-789"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-10-02T08:17:00Z",
"severity": "HIGH"
},
"details": "Memory allocation with excessive size value in the HSS/LMS signature code (HssPublicKeyParameters, HssSignature) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote unauthenticated attacker who can supply both an HSS public key and a signature to cause a denial of service through memory exhaustion via a public key encoding with an excessive level count, because the level count L read when parsing an HSS public key was not checked against the RFC 8554 maximum of 8, and signature parsing then allocated an array of L - 1 entries before reading any further signature data. A single verification can commit up to about 17 GB of memory or fail with an OutOfMemoryException.",
"id": "GHSA-gpr4-c479-xrw4",
"modified": "2026-10-02T09:31:19Z",
"published": "2026-10-02T09:31:19Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-103603"
},
{
"type": "WEB",
"url": "https://github.com/bcgit/bc-csharp/commit/f47ad47c7b5745b53d3f9ac711a5a419a272a5d7"
},
{
"type": "WEB",
"url": "https://github.com/bcgit/bc-csharp/wiki/CVE-2026-103603"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
]
}
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