Bug 2543249 (CVE-2026-42772) - CVE-2026-42772 openssl: openssl: Denial of Service via inefficient QUIC stream reassembly
Summary: CVE-2026-42772 openssl: openssl: Denial of Service via inefficient QUIC strea...
Keywords:
Status: NEW
Alias: CVE-2026-42772
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-09-29 15:53 UTC by OSIDB Bzimport
Modified: 2026-09-29 16:05 UTC (History)
0 users

Fixed In Version:
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Description OSIDB Bzimport 2026-09-29 15:53:15 UTC
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.


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