CVE-2026-19773

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Source

https://cve.org/CVERecord?id=CVE-2026-19773

Import Source

https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-19773.json

JSON Data

https://api.osv.dev/v1/vulns/CVE-2026-19773

Downstream

USN-8893-1

Published

2026-09-15T18:01:09Z

Modified

2026-10-08T07:12:58Z

Severity

9.8 (Critical) CVSS_V3 - CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H CVSS Calculator

Summary

libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability

Details

libwebsockets HTTP/2 HPACK Path Header Parsing Out-Of-Bounds Write Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of libwebsockets. Authentication is not required to exploit this vulnerability.

The specific flaw exists within the parsing of HTTP/2 HPACK path header. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-31036.

Database specific

{
    "cna_assigner": "zdi",
    "cwe_ids": [
        "CWE-787"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/19xxx/CVE-2026-19773.json"
}

References

Affected packages

Git / github.com/warmcat/libwebsockets

Affected ranges

Type

GIT

Repo

https://github.com/warmcat/libwebsockets

Events

Introduced

b4b5aed3903eaff09cd76a410f69bbe5dff66f8e

Fixed

824151862f37bc72f46d9a3e01d5b9408d313a0b

Database specific

Show details

{
    "source": "REFERENCES"
}

Affected versions

Other

b4b5aed3903eaff09cd76a410f69bbe5dff66f8e

Database specific

source

"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-19773.json"

vanir_signatures

[
    {
        "deprecated": false,
        "digest": {
            "line_hashes": [
                "272076028274921666560769073762661966029",
                "289674001653508133457875561273963551729",
                "211806482779604396098642240786168379754"
            ],
            "threshold": 0.9
        },
        "id": "CVE-2026-19773-639e663f",
        "signature_type": "Line",
        "signature_version": "v1",
        "source": "https://github.com/warmcat/libwebsockets/commit/824151862f37bc72f46d9a3e01d5b9408d313a0b",
        "target": {
            "file": "lib/roles/h2/hpack.c"
        }
    },
    {
        "deprecated": false,
        "digest": {
            "function_hash": "249488117909369390949700074553219546391",
            "length": 280
        },
        "id": "CVE-2026-19773-da13717f",
        "signature_type": "Function",
        "signature_version": "v1",
        "source": "https://github.com/warmcat/libwebsockets/commit/824151862f37bc72f46d9a3e01d5b9408d313a0b",
        "target": {
            "file": "lib/roles/h2/hpack.c",
            "function": "lws_frag_append"
        }
    }
]

vanir_signatures_modified

"2026-10-08T07:12:58Z"