CVE-2026-42772 Details
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.
View at NVD
Exploit prediction scoring system (EPSS) score for CVE-2026-42772
EPSS (Exploit Prediction Scoring System): EPSS predicts the likelihood that a vulnerability will be exploited in the wild. A higher percentage means a greater chance of an exploit occurring. The EPSS model produces a probability score between 0 and 1 (0 and 100%).
0.5 Probability of exploitation activity being observed over the next 30 days (43nd percentile)
CVSS score for CVE-2026-42772
CVSS (Common Vulnerability Scoring System): An open framework owned and managed by FIRST.Org, Inc. that assigns a numerical score from 0 to 10 to software vulnerabilities to indicate their severity.
5.3 Medium
Products affected by CVE-2026-42772
OpenSSL 3.4.5
OpenSSL 3.5.7
OpenSSL 3.6.3
OpenSSL 3.4.6
OpenSSL 3.5.8
DVE Score by Bitsight AI
DVE scores complement traditional static scoring systems like CVSS with Bitsight AI powered real-time threat intelligence and underground cyber criminal activity so that security teams can reduce alert fatigue and focus on vulnerabilities most likely to be exploited.
Low
More on DVE scores

CVE-2026-42772 Global Footprint

Top 10 Identified Countries

Country Observations Percentage
US 31,493 36.17%
DE 8,380 9.62%
NL 7,385 8.48%
JP 7,274 8.35%
GB 2,684 3.08%
CA 2,659 3.05%
FR 2,278 2.62%
IE 2,267 2.60%
DK 2,242 2.58%
IN 1,783 2.05%

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CVE-2026-42772 Industry Footprint

Top 10 Identified Industries

*Service provider organizations (typically Technology and Telecommunications) are disproportionally represented in the results given their upstream ownership of end-user infrastructure. See our FAQs.

Industry* Observations Percentage
Technology 46,279 77.09%
Telecommunications 6,371 10.61%
Education 4,004 6.67%
Government/Politics 777 1.29%
Energy/Resources 517 0.86%
Business Services 385 0.64%
Media/Entertainment 307 0.51%
Utilities 240 0.40%
Manufacturing 212 0.35%
Finance 158 0.26%

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