CVE-2026-14456: Unbounded Memory Growth in QUIC Server Incoming Channel Queue
Issue summary: When an OpenSSL QUIC server (Listener SSL object) processes valid QUIC Initial packets for unknown destination connection IDs, it can allocate and queue new incoming channels without enforcing any limit.
Impact summary: A remote peer that can make many Initial packets reach the server listener faster than the application accepts connections, can cause the memory allocated to store the per-channel state to grow without any limits, potentially making the QUIC listener unavailable and causing Denial of Service.
CWE: CWE-770: Allocation of Resources Without Limits or Throttling
Description: The function that handles inbound QUIC packets uses Connection-Id from the packet header to find an existing connection (QUIC channel). If no existing connection is found and the packet type is INITIAL, the function treats the packet as a new connection. It allocates a new channel object and inserts it into a queue where it waits to be accepted by the local application with SSLaccept(3ossl). The memory occupied by these initial channel objects may grow without bounds if the application is not able to call SSLaccept() frequently enough to serve these inbound connection requests.
The issue is present since OpenSSL 3.5 when the QUIC server implementation was added.
The fix introduces a limit for pending connections. The default limit is set to 256 pending connections (waiting to be accepted by the local application). Applications may change the default by calling SSLsetvalueuint(3ossl).
FIPS impact: no The FIPS module is not affected as the QUIC implementation is outside of the OpenSSL FIPS module boundary.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
OpenSSL QUIC server (Listener SSL object)to a version that resolves this vulnerability.Fixed in 3.5 - Configuration
Set/enforce the pending-connection limit for the QUIC server incoming channel queue to 256 pending connections (waiting to be accepted by the local application) to prevent unbounded growth when Initial packets are received without corresponding existing connection IDs and SSL_accept() is not called fast enough.
OpenSSL QUIC server incoming channel queue limit for pending connections = 256
Event History
Frequently Asked Questions
What is the severity of CVE-2026-14456?
The severity of CVE-2026-14456 is rated at 36, indicating a significant risk of unbounded memory growth.
How do I fix CVE-2026-14456?
To fix CVE-2026-14456, you should update your OpenSSL to the latest version that addresses the vulnerability.
What systems are affected by CVE-2026-14456?
CVE-2026-14456 affects OpenSSL QUIC servers that process valid QUIC Initial packets with unknown destination connection IDs.
What is the impact of CVE-2026-14456?
The impact of CVE-2026-14456 is that a remote peer can potentially cause unbounded memory allocation leading to denial of service.
Is CVE-2026-14456 exploitable remotely?
Yes, CVE-2026-14456 is exploitable remotely by sending numerous valid QUIC Initial packets to the affected server.