GHSA-V74W-7MR3-4QG3
Vulnerability from github – Published: 2026-07-24 16:53 – Updated: 2026-08-13 14:25Summary
An attacker can cause Denial of Service by sending a specially crafted malicious XML payload (e.g., repeated </ characters) to a Netty server utilizing XmlFrameDecoder, causing the server's EventLoop thread to exhaust CPU resources and become unresponsive.
Details
io.netty.handler.codec.xml.XmlFrameDecoder suffers from a vulnerability resulting in CPU exhaustion. When < followed by / is encountered, the decoder scans the remaining buffer for a closing >.
Because the parser state is not saved between decode() invocations, an attacker can trickle-feed a payload of </ characters. This forces the decoder to repeatedly rescan the entire accumulated buffer. A 1MB maxFrameLength is enough to completely hang a server's thread while it loops endlessly.
Impact
Denial of Service via CPU Exhaustion. Any application utilizing Netty's XmlFrameDecoder is impacted. An unauthenticated remote attacker can exploit this flaw by sending a modest amount of malformed XML data to an exposed port.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 4.2.15.Final"
},
"package": {
"ecosystem": "Maven",
"name": "io.netty:netty-codec-xml"
},
"ranges": [
{
"events": [
{
"introduced": "4.2.0.Final"
},
{
"fixed": "4.2.16.Final"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 4.1.135.Final"
},
"package": {
"ecosystem": "Maven",
"name": "io.netty:netty-codec-xml"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "4.1.136.Final"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-73507"
],
"database_specific": {
"cwe_ids": [
"CWE-400"
],
"github_reviewed": true,
"github_reviewed_at": "2026-07-24T16:53:04Z",
"nvd_published_at": null,
"severity": "HIGH"
},
"details": "### Summary\nAn attacker can cause Denial of Service by sending a specially crafted malicious XML payload (e.g., repeated `\u003c/` characters) to a Netty server utilizing XmlFrameDecoder, causing the server\u0027s EventLoop thread to exhaust CPU resources and become unresponsive.\n\n### Details\n`io.netty.handler.codec.xml.XmlFrameDecoder` suffers from a vulnerability resulting in CPU exhaustion. When `\u003c` followed by `/` is encountered, the decoder scans the remaining buffer for a closing `\u003e`.\nBecause the parser state is not saved between `decode()` invocations, an attacker can trickle-feed a payload of `\u003c/` characters. This forces the decoder to repeatedly rescan the entire accumulated buffer. A 1MB `maxFrameLength` is enough to completely hang a server\u0027s thread while it loops endlessly.\n\n### Impact\nDenial of Service via CPU Exhaustion. Any application utilizing Netty\u0027s XmlFrameDecoder is impacted. An unauthenticated remote attacker can exploit this flaw by sending a modest amount of malformed XML data to an exposed port.",
"id": "GHSA-v74w-7mr3-4qg3",
"modified": "2026-08-13T14:25:43Z",
"published": "2026-07-24T16:53:04Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/netty/netty/security/advisories/GHSA-v74w-7mr3-4qg3"
},
{
"type": "WEB",
"url": "https://github.com/netty/netty/pull/17063"
},
{
"type": "WEB",
"url": "https://github.com/netty/netty/pull/17065"
},
{
"type": "WEB",
"url": "https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b"
},
{
"type": "WEB",
"url": "https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6"
},
{
"type": "PACKAGE",
"url": "https://github.com/netty/netty"
},
{
"type": "WEB",
"url": "https://github.com/netty/netty/releases/tag/netty-4.1.136.Final"
},
{
"type": "WEB",
"url": "https://github.com/netty/netty/releases/tag/netty-4.2.16.Final"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Netty: Denial of Service in XmlFrameDecoder via CPU Exhaustion"
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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