Vulnerability-Lookup

GHSA-5R49-X3JP-QP9H

Vulnerability from github – Published: 2026-09-29 18:31 – Updated: 2026-09-29 18:31

Details

Impact summary: A remote QUIC peer that completes the handshake can create a connection-scoped CPU pressure and potentially a Denial of Service using compliant STREAM frames inside the advertised receive window, with low attacker bandwidth.

CWE: CWE-407: Inefficient Algorithmic Complexity

Description: OpenSSL manages received QUIC stream fragments using a doubly-linked list. While it optimizes for append operations (at the end of the list), it falls back to a head-to-tail linear search for any fragment that does not immediately follow the current tail.

By manipulating the sequence of offsets, an attacker can force the server to perform O(n^2) operations, consuming excessive CPU time for the QUIC process.

FIPS impact: no The FIPS module is not affected as the QUIC implementation is outside of the OpenSSL FIPS module boundary.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-42772"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-407"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-29T16:17:07Z",
    "severity": null
  },
  "details": "Issue summary: The QUIC stream reassembly algorithm performance deteriorates\nprogressively as packets are arriving out of order. The worst case has\na quadratic complexity proportional to the number of stream frames kept in\nthe buffer for the received stream data.\n\nImpact summary: A remote QUIC peer that completes the handshake can create\na connection-scoped CPU pressure and potentially a Denial of Service using\ncompliant STREAM frames inside the advertised receive window, with low\nattacker bandwidth.\n\nCWE: CWE-407: Inefficient Algorithmic Complexity\n\nDescription: OpenSSL manages received QUIC stream fragments using a\ndoubly-linked list. While it optimizes for append operations (at the end of\nthe list), it falls back to a head-to-tail linear search for any fragment\nthat does not immediately follow the current `tail`.\n\nBy manipulating the sequence of offsets, an attacker can force the server\nto perform O(n^2) operations, consuming excessive CPU time for the\nQUIC process.\n\nFIPS impact: no\nThe FIPS module is not affected as the QUIC implementation is outside of\nthe OpenSSL FIPS module boundary.",
  "id": "GHSA-5r49-x3jp-qp9h",
  "modified": "2026-09-29T18:31:44Z",
  "published": "2026-09-29T18:31:44Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42772"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openssl/openssl/commit/32d0ed8afe1b8c3e7ece725b44663da3d7087a09"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openssl/openssl/commit/ca8402e273af4de5b3f04fa61a0f0c02ce3ae20e"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openssl/openssl/commit/eb2becc0a4baea7f3050a247834d0e5c2ebe1773"
    },
    {
      "type": "WEB",
      "url": "https://github.com/openssl/openssl/commit/f42ae513bbda513b3c121d54834040ee4a0eae1a"
    },
    {
      "type": "WEB",
      "url": "https://openssl-library.org/news/secadv/20260929.txt"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-42772 (GCVE-0-2026-42772)

Vulnerability from cvelistv5 – Published: 2026-09-29 15:32 – Updated: 2026-09-29 15:32

Title

Potential CPU DoS via O(n^2) Fragment Reassembly in QUIC

Summary

Issue summary: The QUIC stream reassembly algorithm performance deteriorates progressively as packets are arriving out of order. The worst case has a quadratic complexity proportional to the number of stream frames kept in the buffer for the received stream data. Impact summary: A remote QUIC peer that completes the handshake can create a connection-scoped CPU pressure and potentially a Denial of Service using compliant STREAM frames inside the advertised receive window, with low attacker bandwidth. CWE: CWE-407: Inefficient Algorithmic Complexity Description: OpenSSL manages received QUIC stream fragments using a doubly-linked list. While it optimizes for append operations (at the end of the list), it falls back to a head-to-tail linear search for any fragment that does not immediately follow the current `tail`. By manipulating the sequence of offsets, an attacker can force the server to perform O(n^2) operations, consuming excessive CPU time for the QUIC process. FIPS impact: no The FIPS module is not affected as the QUIC implementation is outside of the OpenSSL FIPS module boundary.

Severity

No CVSS data available.

CWE

CWE-407 - Inefficient Algorithmic Complexity

Assigner

openssl mitre root Scorecard

References

5 references

URL	Tags
https://openssl-library.org/news/secadv/20260929.txt	vendor-advisory
https://github.com/openssl/openssl/commit/f42ae51…	patch
https://github.com/openssl/openssl/commit/32d0ed8…	patch
https://github.com/openssl/openssl/commit/ca8402e…	patch
https://github.com/openssl/openssl/commit/eb2becc…	patch

Impacted products

1 product

Vendor	Product	Version
OpenSSL	OpenSSL	Affected: 4.0.0 , < 4.0.3 (semver) Affected: 3.6.0 , < 3.6.5 (semver) Affected: 3.5.0 , < 3.5.9 (semver) Affected: 3.4.0 , < 3.4.8 (semver)

Date Public

2026-09-29 14:21

Credits

Saku0512 Opal Wright (Trail of Bits) Alexandr Nedvedicky

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "OpenSSL",
          "vendor": "OpenSSL",
          "versions": [
            {
              "lessThan": "4.0.3",
              "status": "affected",
              "version": "4.0.0",
              "versionType": "semver"
            },
            {
              "lessThan": "3.6.5",
              "status": "affected",
              "version": "3.6.0",
              "versionType": "semver"
            },
            {
              "lessThan": "3.5.9",
              "status": "affected",
              "version": "3.5.0",
              "versionType": "semver"
            },
            {
              "lessThan": "3.4.8",
              "status": "affected",
              "version": "3.4.0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "reporter",
          "value": "Saku0512"
        },
        {
          "lang": "en",
          "type": "reporter",
          "value": "Opal Wright (Trail of Bits)"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Alexandr Nedvedicky"
        }
      ],
      "datePublic": "2026-09-29T14:21:57.000Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "Issue summary: The QUIC stream reassembly algorithm performance deteriorates\u003cbr\u003eprogressively as packets are arriving out of order. The worst case has\u003cbr\u003ea quadratic complexity proportional to the number of stream frames kept in\u003cbr\u003ethe buffer for the received stream data.\u003cbr\u003e\u003cbr\u003eImpact summary: A remote QUIC peer that completes the handshake can create\u003cbr\u003ea connection-scoped CPU pressure and potentially a Denial of Service using\u003cbr\u003ecompliant STREAM frames inside the advertised receive window, with low\u003cbr\u003eattacker bandwidth.\u003cbr\u003e\u003cbr\u003eCWE: CWE-407: Inefficient Algorithmic Complexity\u003cbr\u003e\u003cbr\u003eDescription: OpenSSL manages received QUIC stream fragments using a\u003cbr\u003edoubly-linked list. While it optimizes for append operations (at the end of\u003cbr\u003ethe list), it falls back to a head-to-tail linear search for any fragment\u003cbr\u003ethat does not immediately follow the current `tail`.\u003cbr\u003e\u003cbr\u003eBy manipulating the sequence of offsets, an attacker can force the server\u003cbr\u003eto perform O(n^2) operations, consuming excessive CPU time for the\u003cbr\u003eQUIC process.\u003cbr\u003e\u003cbr\u003eFIPS impact: no\u003cbr\u003eThe FIPS module is not affected as the QUIC implementation is outside of\u003cbr\u003ethe OpenSSL FIPS module boundary."
            }
          ],
          "value": "Issue summary: The QUIC stream reassembly algorithm performance deteriorates\nprogressively as packets are arriving out of order. The worst case has\na quadratic complexity proportional to the number of stream frames kept in\nthe buffer for the received stream data.\n\nImpact summary: A remote QUIC peer that completes the handshake can create\na connection-scoped CPU pressure and potentially a Denial of Service using\ncompliant STREAM frames inside the advertised receive window, with low\nattacker bandwidth.\n\nCWE: CWE-407: Inefficient Algorithmic Complexity\n\nDescription: OpenSSL manages received QUIC stream fragments using a\ndoubly-linked list. While it optimizes for append operations (at the end of\nthe list), it falls back to a head-to-tail linear search for any fragment\nthat does not immediately follow the current `tail`.\n\nBy manipulating the sequence of offsets, an attacker can force the server\nto perform O(n^2) operations, consuming excessive CPU time for the\nQUIC process.\n\nFIPS impact: no\nThe FIPS module is not affected as the QUIC implementation is outside of\nthe OpenSSL FIPS module boundary."
        }
      ],
      "metrics": [
        {
          "format": "other",
          "other": {
            "content": {
              "text": "Low"
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            "type": "https://openssl-library.org/policies/general/security-policy/"
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              "lang": "en",
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      "providerMetadata": {
        "dateUpdated": "2026-09-29T15:32:14.009Z",
        "orgId": "3a12439a-ef3a-4c79-92e6-6081a721f1e5",
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        },
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          "name": "4.0.3 git commit",
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          "url": "https://github.com/openssl/openssl/commit/f42ae513bbda513b3c121d54834040ee4a0eae1a"
        },
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          "name": "3.6.5 git commit",
          "tags": [
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            "patch"
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          "url": "https://github.com/openssl/openssl/commit/eb2becc0a4baea7f3050a247834d0e5c2ebe1773"
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      "source": {
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    "assignerShortName": "openssl",
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    "datePublished": "2026-09-29T15:32:14.009Z",
    "dateReserved": "2026-04-29T09:22:27.969Z",
    "dateUpdated": "2026-09-29T15:32:14.009Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

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Confirmed: The vulnerability has been validated from an analyst's perspective.
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Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
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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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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GHSA-5R49-X3JP-QP9H

CVE-2026-42772 (GCVE-0-2026-42772)

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