CVE-2026-84784
Description
A flaw was found in OpenSSL. A remote attacker can cause a Denial of Service (DoS) by flooding a connection with connection identifier update requests while withholding acknowledgments. This behavior bypasses connection limits and forces the system to accumulate pending retirement frames, resulting in excessive memory consumption.
Statement
This issue is rated Moderate because a remote QUIC peer can force unbounded growth of pending RETIRE_CONNECTION_ID control frames when acknowledgments are withheld, but the practical impact is limited memory pressure (on the order of hundreds of megabytes per connection depending on ACK delay) rather than a reliable full service outage. There is no confidentiality or integrity impact. The flaw is confined to the OpenSSL QUIC stack (outside the FIPS module); OpenSSL 3.0, 1.1.1, and 1.0.2 are not affected upstream. Red Hat scores CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L (5.3), reflecting Limited Availability rather than High.
Mitigation
If QUIC is not required, disable it in the application or reverse proxy configuration. Restrict untrusted QUIC/UDP peers that can complete or attempt a handshake ([CME-202](https://cmetaxonomy.org/entries/CME-202.html)). Apply the fixed OpenSSL packages (upstream 3.4.8, 3.5.9, 3.6.5, or 4.0.3 and later) when available for affected streams.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | N/A | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | Low | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Resource Consumption (Other)
When allocating resources without limits, an attacker could prevent other systems, applications, or processes from accessing the same type of resource. It can be easy for an attacker to consume many resources by rapidly making many requests or causing larger resources to be used than is needed.
Frequently Asked Questions
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