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      "text": "Copyright \u00a9 Red Hat, Inc. All rights reserved.",
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        "url": "https://www.first.org/tlp/"
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    "lang": "en",
    "notes": [
      {
        "category": "summary",
        "text": "An updated version of Red Hat Update Infrastructure (RHUI) is now\navailable. RHUI 4.11.4 resolves a security vulnerability in pyOpenSSL.",
        "title": "Topic"
      },
      {
        "category": "general",
        "text": "Red Hat Update Infrastructure (RHUI) provides a highly scalable and redundant framework for managing repositories and content. It also allows cloud providers to deliver content and updates to Red Hat Enterprise Linux (RHEL) instances.\n\nSecurity Fixes:\n* pyOpenSSL: DTLS cookie callback buffer overflow (CVE-2026-27459)",
        "title": "Details"
      },
      {
        "category": "legal_disclaimer",
        "text": "This content is licensed under the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/). If you distribute this content, or a modified version of it, you must provide attribution to Red Hat Inc. and provide a link to the original.",
        "title": "Terms of Use"
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        "url": "https://access.redhat.com/errata/RHSA-2026:10754"
      },
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        "summary": "2448503",
        "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2448503"
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        "url": "https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_10754.json"
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    "title": "Red Hat Security Advisory: RHUI 4.11.4 security update - python-pyOpenSSL",
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      "current_release_date": "2026-05-07T21:42:10+00:00",
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      "id": "RHSA-2026:10754",
      "initial_release_date": "2026-04-27T10:15:08+00:00",
      "revision_history": [
        {
          "date": "2026-04-27T10:15:08+00:00",
          "number": "1",
          "summary": "Initial version"
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        {
          "date": "2026-04-27T10:15:08+00:00",
          "number": "2",
          "summary": "Last updated version"
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        {
          "date": "2026-05-07T21:42:10+00:00",
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                "name": "RHUI 4 for RHEL 8",
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  "vulnerabilities": [
    {
      "cve": "CVE-2026-27459",
      "cwe": {
        "id": "CWE-120",
        "name": "Buffer Copy without Checking Size of Input (\u0027Classic Buffer Overflow\u0027)"
      },
      "discovery_date": "2026-03-18T00:01:41.404915+00:00",
      "ids": [
        {
          "system_name": "Red Hat Bugzilla ID",
          "text": "2448503"
        }
      ],
      "notes": [
        {
          "category": "description",
          "text": "A flaw was found in pyOpenSSL. The set_cookie_generate_callback callback function can be used to generate DTLS cookies. When the callback returns a cookie string or byte sequence longer than 256 bytes, a buffer overflow can be triggered due to a missing bounds checking before copying the data to a fixed-size buffer provided by the underlying OpenSSL library.",
          "title": "Vulnerability description"
        },
        {
          "category": "summary",
          "text": "pyOpenSSL: DTLS cookie callback buffer overflow",
          "title": "Vulnerability summary"
        },
        {
          "category": "other",
          "text": "This flaw is only exploitable when an application using the pyOpenSSL library provides a custom callback to the set_cookie_generate_callback function. For the buffer overflow to occur, the callback function must return a cookie string or byte sequence longer than 256 bytes, limiting the exposure of this issue. Due to these reasons, this vulnerability has been rated with an important severity.",
          "title": "Statement"
        },
        {
          "category": "general",
          "text": "The CVSS score(s) listed for this vulnerability do not reflect the associated product\u0027s status, and are included for informational purposes to better understand the severity of this vulnerability.",
          "title": "CVSS score applicability"
        }
      ],
      "product_status": {
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        ]
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          "url": "https://access.redhat.com/security/cve/CVE-2026-27459"
        },
        {
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          "summary": "RHBZ#2448503",
          "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2448503"
        },
        {
          "category": "external",
          "summary": "https://www.cve.org/CVERecord?id=CVE-2026-27459",
          "url": "https://www.cve.org/CVERecord?id=CVE-2026-27459"
        },
        {
          "category": "external",
          "summary": "https://nvd.nist.gov/vuln/detail/CVE-2026-27459",
          "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27459"
        },
        {
          "category": "external",
          "summary": "https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst",
          "url": "https://github.com/pyca/pyopenssl/blob/358cbf29c4e364c59930e53a270116249581eaa3/CHANGELOG.rst"
        },
        {
          "category": "external",
          "summary": "https://github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408",
          "url": "https://github.com/pyca/pyopenssl/commit/57f09bb4bb051d3bc2a1abd36e9525313d5cd408"
        },
        {
          "category": "external",
          "summary": "https://github.com/pyca/pyopenssl/security/advisories/GHSA-5pwr-322w-8jr4",
          "url": "https://github.com/pyca/pyopenssl/security/advisories/GHSA-5pwr-322w-8jr4"
        }
      ],
      "release_date": "2026-03-17T23:34:28.483000+00:00",
      "remediations": [
        {
          "category": "vendor_fix",
          "date": "2026-04-27T10:15:08+00:00",
          "details": "Before applying this update, make sure all previously released errata relevant\nto your system have been applied.\n\nFor detailed instructions on how to apply this update, see:\nhttps://docs.redhat.com/en/documentation/red_hat_update_infrastructure/4/html/migrating_red_hat_update_infrastructure/assembly_upgrading-red-hat-update-infrastructure_migrating-red-hat-update-infrastructure\n\nNote: While there is no updated version of rhui-installer, for this update to take effect, it is necessary to rerun rhui-installer on the RHUA node and to reinstall the CDS nodes, as described in the documentation.\n\nFor other information, see the product documentation:\nhttps://docs.redhat.com/en/documentation/red_hat_update_infrastructure/4",
          "product_ids": [
            "8Base-RHUI-4:python-pyOpenSSL-0:24.1.0-2.el8ui.src",
            "8Base-RHUI-4:python3.11-pyOpenSSL-0:24.1.0-2.el8ui.noarch"
          ],
          "restart_required": {
            "category": "none"
          },
          "url": "https://access.redhat.com/errata/RHSA-2026:10754"
        },
        {
          "category": "workaround",
          "details": "To mitigate this flaw, ensure the callback provided to the set_cookie_generate_callback function strictly limits the returned cookie string or byte sequence to under 256 bytes.",
          "product_ids": [
            "8Base-RHUI-4:python-pyOpenSSL-0:24.1.0-2.el8ui.src",
            "8Base-RHUI-4:python3.11-pyOpenSSL-0:24.1.0-2.el8ui.noarch"
          ]
        }
      ],
      "scores": [
        {
          "cvss_v3": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "HIGH",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "products": [
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          ]
        }
      ],
      "threats": [
        {
          "category": "impact",
          "details": "Important"
        }
      ],
      "title": "pyOpenSSL: DTLS cookie callback buffer overflow"
    }
  ]
}