CVE-2026-42772

Public on 2026-09-29
Modified on 2026-09-30
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.
Severity
Medium severity
Medium
See what this means
CVSS v3 Base Score
5.3
See breakdown

Affected Packages

Platform Package Release Date Advisory Status
Amazon Linux 2 - Core edk2 Not Affected
Amazon Linux 2023 edk2 Not Affected
Amazon Linux 2 - Core openssl Not Affected
Amazon Linux 2023 openssl Pending Fix
Amazon Linux 2027 Preview openssl Pending Fix
Amazon Linux 2 - Openssl-snapsafe Extra openssl-snapsafe Not Affected
Amazon Linux 2 - Core openssl11 Not Affected

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L