Skip to main content
← All vulnerabilities
CVE-2026-42772

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

Published
Last modified
published
Not listed in CISA KEV
Low (openssl)
Fix
Fixed in 4.0.3, 3.6.5, 3.5.9, 3.4.8
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: partial

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: partial

  3. Record last updated

Affected versions

  • OpenSSL OpenSSL

    From 4.0.0 · fixed in 4.0.3; From 3.6.0 · fixed in 3.6.5; From 3.5.0 · fixed in 3.5.9; From 3.4.0 · fixed in 3.4.8

References 5

openssl-library.org

GitHub · openssl/openssl