CVE-2026-34183
Description
A flaw was found in OpenSSL's QUIC PATH_CHALLENGE handler. A remote attacker can exploit this vulnerability by flooding a QUIC client or server with specially crafted PATH_CHALLENGE frames. This leads to unbounded memory allocation within the local QUIC stack, as the system continuously allocates PATH_RESPONSE frames without them being acknowledged. The primary consequence is a Denial of Service (DoS), causing the affected application to terminate abnormally due to memory exhaustion.
Statement
A Moderate severity flaw exists in the QUIC PATH_CHALLENGE handler, allowing a remote attacker to exhaust heap memory of a QUIC client or server. By flooding the local QUIC stack with PATH_CHALLENGE frames, a malicious peer can trigger unbounded memory allocation, leading to a denial of service for applications utilizing the vulnerable QUIC implementation.
Mitigation
To mitigate this vulnerability, apply UDP rate limiting at your network edge to throttle malicious traffic. If QUIC is not strictly required, disable the listener entirely and configure your application to use standard TLS over TCP. Additionally, enforce strict process memory limits using cgroups to prevent host-wide memory exhaustion during an attack.
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 | 7.5 | 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 | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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
Not sure what something means? Check out our Security Glossary.
Want to get errata notifications? Sign up here.
