CVE-2026-55831 (GCVE-0-2026-55831)

Vulnerability from cvelistv5 – Published: 2026-07-20 23:00 – Updated: 2026-07-20 23:00
VLAI
Title
Netty SPDY SETTINGS frame count materializes unbounded settings map
Summary
Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty's SPDY SETTINGS decoder accepts a peer-declared SETTINGS entry count up to the 24-bit frame-length limit and materializes every unique setting ID in `DefaultSpdySettingsFrame`, allowing a remote SPDY/3.1 peer to send a syntactically valid roughly 2 MiB SETTINGS frame that creates 262144 map entries and amplifies network input into heap growth and ordered-map insertion work. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE
  • CWE-770 - Allocation of Resources Without Limits or Throttling
  • CWE-400 - Uncontrolled Resource Consumption
Assigner
References
Impacted products
Vendor Product Version
netty netty Affected: >= 4.2.0.Final, < 4.2.16.Final
Affected: >= 4.1.0.Final, < 4.1.136.Final
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        {
          "product": "netty",
          "vendor": "netty",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 4.2.0.Final, \u003c 4.2.16.Final"
            },
            {
              "status": "affected",
              "version": "\u003e= 4.1.0.Final, \u003c 4.1.136.Final"
            }
          ]
        }
      ],
      "descriptions": [
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          "value": "Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty\u0027s SPDY SETTINGS decoder accepts a peer-declared SETTINGS entry count up to the 24-bit frame-length limit and materializes every unique setting ID in `DefaultSpdySettingsFrame`, allowing a remote SPDY/3.1 peer to send a syntactically valid roughly 2 MiB SETTINGS frame that creates 262144 map entries and amplifies network input into heap growth and ordered-map insertion work. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final."
        }
      ],
      "metrics": [
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          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
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            }
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        {
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      "providerMetadata": {
        "dateUpdated": "2026-07-20T23:00:31.859Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
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      "references": [
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          "name": "https://github.com/netty/netty/security/advisories/GHSA-6jqx-86gh-f27w",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/netty/netty/security/advisories/GHSA-6jqx-86gh-f27w"
        },
        {
          "name": "https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b"
        },
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          "name": "https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6",
          "tags": [
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          ],
          "url": "https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6"
        },
        {
          "name": "https://github.com/netty/netty/releases/tag/netty-4.1.136.Final",
          "tags": [
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          "url": "https://github.com/netty/netty/releases/tag/netty-4.1.136.Final"
        },
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          "tags": [
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          "url": "https://github.com/netty/netty/releases/tag/netty-4.2.16.Final"
        }
      ],
      "source": {
        "advisory": "GHSA-6jqx-86gh-f27w",
        "discovery": "UNKNOWN"
      },
      "title": "Netty SPDY SETTINGS frame count materializes unbounded settings map"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-55831",
    "datePublished": "2026-07-20T23:00:31.859Z",
    "dateReserved": "2026-06-17T16:29:38.864Z",
    "dateUpdated": "2026-07-20T23:00:31.859Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-55831",
      "date": "2026-07-21",
      "epss": "0.0063",
      "percentile": "0.46225"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-55831\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-07-21T00:17:35.383\",\"lastModified\":\"2026-07-21T20:25:45.920\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"Netty is a network application framework for development of protocol servers and clients. Prior to 4.1.136.Final and 4.2.16.Final, Netty\u0027s SPDY SETTINGS decoder accepts a peer-declared SETTINGS entry count up to the 24-bit frame-length limit and materializes every unique setting ID in `DefaultSpdySettingsFrame`, allowing a remote SPDY/3.1 peer to send a syntactically valid roughly 2 MiB SETTINGS frame that creates 262144 map entries and amplifies network input into heap growth and ordered-map insertion work. This issue is fixed in versions 4.1.136.Final and 4.2.16.Final.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"netty\",\"product\":\"netty\",\"versions\":[{\"version\":\"\u003e= 4.2.0.Final, \u003c 4.2.16.Final\",\"status\":\"affected\"},{\"version\":\"\u003e= 4.1.0.Final, \u003c 4.1.136.Final\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-400\"},{\"lang\":\"en\",\"value\":\"CWE-770\"}]}],\"references\":[{\"url\":\"https://github.com/netty/netty/commit/5b68c61f37aa4a3045cba624cbea239655c9003b\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/netty/netty/commit/bb2ff68a1fb71cb4b0eb9a9e17b66c52aff680c6\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/netty/netty/releases/tag/netty-4.1.136.Final\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/netty/netty/releases/tag/netty-4.2.16.Final\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/netty/netty/security/advisories/GHSA-6jqx-86gh-f27w\",\"source\":\"security-advisories@github.com\"}]}}"
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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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.


Detection rules are retrieved from Rulezet.