{
  "cveId": "CVE-2026-63075",
  "url": "https://patchblox.com/security/cve/CVE-2026-63075",
  "summary": "CVE-2026-63075 is fixed in 14 products on 1 platform, first by libssl3t64 3.5.5-1ubuntu3.4, released August 24, 2026. It is not reported as exploited. Patch Radar priority: High.",
  "title": "QUIC ACK-only Packet Retention Can Cause Memory Exhaustion",
  "description": "Issue summary: When OpenSSL processes QUIC traffic from a peer that repeatedly sends ack-eliciting packets while not acknowledging ACK-only responses, the QUIC stack can retain ACK-only packet metadata for the lifetime of the connection.  Impact summary: A remote peer that can complete a QUIC handshake can cause connection-scoped memory growth which may lead to Denial of Service through memory exhaustion, especially with sustained traffic or many concurrent QUIC connections.  CWE: CWE-770: Allocation of Resources Without Limits or Throttling  Description: When the OpenSSL QUIC stack sends an ACK-only packet, there is no requirement by the QUIC protocol that the peer will acknowledge that ACK-only packet (i.e. it is itself not ack-eliciting). However, the OpenSSL implementation stores the metadata about the ACK frames regardless. In and of itself that\u0027s ok, but if a malicious peer establishes a connection, and then drives the connection such that ACK-only packets are forced from the  OpenSSL implementation peer (i.e., by sending numerous PING frames), and then withholding any subsequent acks for ack-eliciting data, like legitimate data, said malicious peer can force inappropriate memory growth on the OpenSSL peer, potentially leading to a Denial of Service.  The fix is to ensure that we account for the transmission of the ACK-only packet in the packet histories high and low watermark without actually storing the ACK-only packet metadata itself.  FIPS impact: no The OpenSSL FIPS module is not affected as the QUIC code is outside the FIPS module boundary.",
  "published": "2026-08-24T17:00:00Z",
  "severity": "Important",
  "cvss": 7.5,
  "cvssVector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
  "cwe": "Allocation of Resources Without Limits or Throttling",
  "epss": 0.0057,
  "epssPercentile": 0.47468,
  "priority": "High",
  "priorityTier": 3,
  "exploited": false,
  "vendorExploited": false,
  "disclosed": false,
  "vendorAdvisory": "https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-63075",
  "fixes": [
    {
      "platform": "linux",
      "product": "libssl3t64",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "3.5.5-1ubuntu3.4",
      "fix": "libssl3t64 3.5.5-1ubuntu3.4",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-libssl3t64-3.5.5-1ubuntu3.4",
      "released": "2026-08-24T17:00:00Z"
    },
    {
      "platform": "linux",
      "product": "openssl",
      "release": "Debian 13.5 (trixie)",
      "fixedVersion": "3.5.7-1~deb13u2",
      "fix": "DEBIAN-CVE-2026-63075",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-63075",
      "released": "2026-08-26T00:17:14Z"
    },
    {
      "platform": "linux",
      "product": "openssl",
      "release": "Debian 14",
      "fixedVersion": "3.6.4-1",
      "fix": "DEBIAN-CVE-2026-63075",
      "url": "https://patchblox.com/security/fix/linux/debian-cve-2026-63075",
      "released": "2026-08-26T00:17:14Z"
    },
    {
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      "product": "openssl",
      "release": "RHEL 10",
      "fixedVersion": "3.5.8-1.el10_2",
      "fix": "RHSA-2026:67154",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2026-67154",
      "released": "2026-09-14T12:58:54Z"
    },
    {
      "platform": "linux",
      "product": "openssl",
      "release": "RHEL 9",
      "fixedVersion": "1:3.5.8-1.el9_8",
      "fix": "RHSA-2026:67165",
      "url": "https://patchblox.com/security/fix/linux/rhsa-2026-67165",
      "released": "2026-09-19T18:32:55Z"
    },
    {
      "platform": "linux",
      "product": "openssl",
      "release": "Ubuntu 26.04.1 LTS (resolute)",
      "fixedVersion": "3.5.5-1ubuntu3.4",
      "fix": "openssl 3.5.5-1ubuntu3.4",
      "url": "https://patchblox.com/security/fix/linux/ubuntu-resolute-openssl-3.5.5-1ubuntu3.4",
      "released": "2026-08-24T17:00:00Z"
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    {
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      "product": "openssl",
      "release": "almalinux 10",
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      "fix": "ALSA-2026:67154",
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      "released": "2026-09-14T00:00:00Z"
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      "fix": "RLSA-2026:67154",
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      "released": "2026-09-02T15:55:21Z"
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      "released": "2026-09-07T08:29:17Z"
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      "released": "2026-09-02T15:59:12Z"
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      "released": "2026-09-14T09:00:00Z"
    }
  ],
  "noFixYet": [],
  "dataAsOf": "2026-11-09T01:18:40Z",
  "attribution": {
    "text": "Data: Patchblox Patch Radar",
    "url": "https://patchblox.com/security/patch-radar",
    "terms": "https://patchblox.com/security/patch-radar/use-the-data"
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}