{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "ch.qos.logback:logback-core"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.5.25"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-1225"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-20"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-01-22T18:06:44Z",
    "nvd_published_at": "2026-01-22T10:16:07Z",
    "severity": "LOW"
  },
  "details": "ACE vulnerability in configuration file processing  by QOS.CH logback-core up to and including version 1.5.24 in Java applications, allows an attacker to instantiate classes already present on the class path by compromising an existing logback configuration file.\n\nThe instantiation of a potentially malicious Java class requires that said class is present on the user\u0027s class-path. In addition, the attacker must  have write access to a configuration file. However, after successful instantiation, the instance is very likely to be discarded with no further ado.",
  "id": "GHSA-qqpg-mvqg-649v",
  "modified": "2026-01-22T18:06:44Z",
  "published": "2026-01-22T12:31:22Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-1225"
    },
    {
      "type": "WEB",
      "url": "https://github.com/qos-ch/logback/issues/997"
    },
    {
      "type": "WEB",
      "url": "https://github.com/qos-ch/logback/commit/1f97ae1844b1be8486e4e9cade98d7123d3eded5"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/qos-ch/logback"
    },
    {
      "type": "WEB",
      "url": "https://logback.qos.ch/news.html#1.5.25"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:L/AC:H/AT:P/PR:H/UI:N/VC:L/VI:L/VA:L/SC:L/SI:L/SA:L",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Logback allows an attacker to instantiate classes already present on the class path"
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "io.netty:netty-codec-http2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.1.132.Final"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c 4.2.10.Final"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "io.netty:netty-codec-http2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.2.0.Alpha1"
            },
            {
              "fixed": "4.2.11.Final"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33871"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-03-26T18:49:21Z",
    "nvd_published_at": "2026-03-27T20:16:34Z",
    "severity": "HIGH"
  },
  "details": "### Summary\nA remote user can trigger a Denial of Service (DoS) against a Netty HTTP/2 server by sending a flood of `CONTINUATION` frames. The server\u0027s lack of a limit on the number of `CONTINUATION` frames, combined with a bypass of existing size-based mitigations using zero-byte frames, allows an user to cause excessive CPU consumption with minimal bandwidth, rendering the server unresponsive.\n\n### Details\nThe vulnerability exists in Netty\u0027s `DefaultHttp2FrameReader`. When an HTTP/2 `HEADERS` frame is received without the `END_HEADERS` flag, the server expects one or more subsequent `CONTINUATION` frames. However, the implementation does not enforce a limit on the *count* of these `CONTINUATION` frames.\n\nThe key issue is located in `codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameReader.java`. The `verifyContinuationFrame()` method checks for stream association but fails to implement a frame count limit.\n\nAny user can exploit this by sending a stream of `CONTINUATION` frames with a zero-byte payload. While Netty has a `maxHeaderListSize` protection to limit the total size of headers, this check is never triggered by zero-byte frames. The logic effectively evaluates to `maxHeaderListSize - 0 \u003c currentSize`, which will not trigger the limit until a non-zero byte is added. As a result, the server is forced to process an unlimited number of frames, consuming a CPU thread and monopolizing the connection.\n\n`codec-http2/src/main/java/io/netty/handler/codec/http2/DefaultHttp2FrameReader.java`\n\n**`verifyContinuationFrame()` (lines 381-393)** \u2014 No frame count check:\n```java\nprivate void verifyContinuationFrame() throws Http2Exception {\n    verifyAssociatedWithAStream();\n    if (headersContinuation == null) {\n        throw connectionError(PROTOCOL_ERROR, \"...\");\n    }\n    if (streamId != headersContinuation.getStreamId()) {\n        throw connectionError(PROTOCOL_ERROR, \"...\");\n    }\n    // NO frame count limit!\n}\n```\n\n**`HeadersBlockBuilder.addFragment()` (lines 695-723)** \u2014 Byte limit bypassed by 0-byte frames:\n```java\n// Line 710-711: This check NEVER fires when len=0\nif (headersDecoder.configuration().maxHeaderListSizeGoAway() - len \u003c\n        headerBlock.readableBytes()) {\n    headerSizeExceeded();  // 10240 - 0 \u003c 1 =\u003e FALSE always\n}\n```\n\nWhen `len=0`: `maxGoAway - 0 \u003c readableBytes` \u2192 `10240 \u003c 1` \u2192 FALSE. The byte limit is never triggered.\n\n### Impact\nThis is a CPU-based Denial of Service (DoS). Any service using Netty\u0027s default HTTP/2 server implementation is impacted. An unauthenticated user can exhaust server CPU resources and block legitimate users, leading to service unavailability. The low bandwidth requirement for the attack makes it highly practical.",
  "id": "GHSA-w9fj-cfpg-grvv",
  "modified": "2026-03-27T21:48:53Z",
  "published": "2026-03-26T18:49:21Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/netty/netty/security/advisories/GHSA-w9fj-cfpg-grvv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33871"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/netty/netty"
    }
  ],
  "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Netty HTTP/2 CONTINUATION Frame Flood DoS via Zero-Byte Frame Bypass"
}

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 4.1.114.Final"
      },
      "package": {
        "ecosystem": "Maven",
        "name": "io.netty:netty-common"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "4.1.115.Final"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2024-47535"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2024-11-12T19:53:17Z",
    "nvd_published_at": "2024-11-12T16:15:22Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nAn unsafe reading of environment file could potentially cause a denial of service in Netty.\nWhen loaded on an Windows application, Netty attemps to load a file that does not exist. If an attacker creates such a large file, the Netty application crash.\n\n\n### Details\n\nWhen the library netty is loaded in a java windows application, the library tries to identify the system environnement in which it is executed.\n\nAt this stage, Netty tries to load both `/etc/os-release` and `/usr/lib/os-release` even though it is in a Windows environment. \n\n\u003cimg width=\"364\" alt=\"1\" src=\"https://github.com/user-attachments/assets/9466b181-9394-45a3-b0e3-1dcf105def59\"\u003e\n\nIf netty finds this files, it reads them and loads them into memory.\n\nBy default :\n\n- The JVM maximum memory size is set to 1 GB,\n- A non-privileged user can create a directory at `C:\\` and create files within it.\n\n\u003cimg width=\"340\" alt=\"2\" src=\"https://github.com/user-attachments/assets/43b359a2-5871-4592-ae2b-ffc40ac76831\"\u003e\n\n\u003cimg width=\"523\" alt=\"3\" src=\"https://github.com/user-attachments/assets/ad5c6eed-451c-4513-92d5-ba0eee7715c1\"\u003e\n\nthe source code identified :\nhttps://github.com/netty/netty/blob/4.1/common/src/main/java/io/netty/util/internal/PlatformDependent.java\n\nDespite the implementation of the function `normalizeOs()` the source code not verify the OS before reading `C:\\etc\\os-release` and `C:\\usr\\lib\\os-release`.\n\n### PoC\n\nCreate a file larger than 1 GB of data in `C:\\etc\\os-release` or `C:\\usr\\lib\\os-release` on a Windows environnement and start your Netty application.\n\nTo observe what the application does with the file, the security analyst used \"Process Monitor\" from the \"Windows SysInternals\" suite. (https://learn.microsoft.com/en-us/sysinternals/)\n\n```\ncd C:\\etc\nfsutil file createnew os-release 3000000000\n```\n\n\u003cimg width=\"519\" alt=\"4\" src=\"https://github.com/user-attachments/assets/39df22a3-462b-4fd0-af9a-aa30077ec08f\"\u003e\n\n\u003cimg width=\"517\" alt=\"5\" src=\"https://github.com/user-attachments/assets/129dbd50-fc36-4da5-8eb1-582123fb528f\"\u003e\n\nThe source code used is the Netty website code example : [Echo \u2010 the very basic client and server](https://netty.io/4.1/xref/io/netty/example/echo/package-summary.html).\n\nThe vulnerability was tested on the 4.1.112.Final version.\n\nThe security analyst tried the same technique for `C:\\proc\\sys\\net\\core\\somaxconn` with a lot of values to impact Netty but the only things that works is the \"larger than 1 GB file\" technique. https://github.com/netty/netty/blob/c0fdb8e9f8f256990e902fcfffbbe10754d0f3dd/common/src/main/java/io/netty/util/NetUtil.java#L186\n\n### Impact\n\nBy loading the \"file larger than 1 GB\" into the memory, the Netty library exceeds the JVM memory limit and causes a crash in the java Windows application.\n\nThis behaviour occurs 100% of the time in both Server mode and Client mode if the large file exists.\n\nClient mode :\n\n\u003cimg width=\"449\" alt=\"6\" src=\"https://github.com/user-attachments/assets/f8fe1ed0-1a42-4490-b9ed-dbc9af7804be\"\u003e\n\nServer mode :\n\n\u003cimg width=\"464\" alt=\"7\" src=\"https://github.com/user-attachments/assets/b34b42bd-4fbd-4170-b93a-d29ba87b88eb\"\u003e\n\nsomaxconn :\n\n\u003cimg width=\"532\" alt=\"8\" src=\"https://github.com/user-attachments/assets/0656b3bb-32c6-4ae2-bff7-d93babba08a3\"\u003e\n\n### Severity\n\n- Attack vector : \"Local\" because the attacker needs to be on the system where the Netty application is running.\n- Attack complexity : \"Low\" because the attacker only need to create a massive file (regardless of its contents).\n- Privileges required : \"Low\" because the attacker requires a user account to exploit the vulnerability.\n- User intercation : \"None\" because the administrator don\u0027t need to accidentally click anywhere to trigger the vulnerability. Furthermore, the exploitation works with defaults windows/AD settings.\n- Scope : \"Unchanged\" because only Netty is affected by the vulnerability.\n- Confidentiality : \"None\" because no data is exposed through exploiting the vulnerability.\n- Integrity : \"None\" because the explotation of the vulnerability does not allow editing, deleting or adding data elsewhere.\n- Availability : \"High\" because the exploitation of this vulnerability crashes the entire java application.",
  "id": "GHSA-xq3w-v528-46rv",
  "modified": "2025-02-18T15:57:45Z",
  "published": "2024-11-12T19:53:17Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/netty/netty/security/advisories/GHSA-xq3w-v528-46rv"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-47535"
    },
    {
      "type": "WEB",
      "url": "https://github.com/netty/netty/commit/fbf7a704a82e7449b48bd0bbb679f5661c6d61a3"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/netty/netty"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Denial of Service attack on windows app using netty"
}