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[ CVE-2026-42772 · Published 29 Sep 2026 ]

Vulnerability in OpenSSL

CVSS 5.3 EPSS <1%2 agency advisoriesFix available

[ Description ]Official description

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.

[ Fixes ]Fixes and patches

[ Advisories ]Government CERT advisories

  • CERT-FRCERTFR-2026-AVI-1241

    Multiple vulnerabilities in OpenSSL Translated from French

    Multiple vulnerabilities have been discovered in OpenSSL. Some of them allow an attacker to cause remote denial of service, a breach of data confidentiality and a breach of data integrity.

    CVE-2026-75806CVE-2026-77696CVE-2026-35189+11 more CVEs
  • BSI CERT-BundWID-SEC-2026-3638

    OpenSSL: Multiple vulnerabilities Translated from German

    Risk highCVE-2026-35189CVE-2026-84784CVE-2026-75805+11 more CVEs

[ References ]References