Issue summary: A malicious remote peer may flood the local QUIC stack with NEW_CONNECTION_ID frames by avoiding a limit check on how many connection IDs the remote QUIC stack can use. Impact summary: The local QUIC stack sends a RETIRE_CONN_ID frame for every NEW_CONNECTION_ID frame it receives. The RETIRE_CONN_ID frame is dispatched via the Control Frame Queue (CFQ). If the remote peer also withholds ACKs, then it can force the local stack to allocate ~400MB (depending on ACK delay). CWE: CWE-770: Allocation of Resources Without Limits or Throttling Description: RFC 9000 sections 5.1.1 and 5.1.2 [1] describe the mechanism by which a remote peer can notify the local QUIC stack to change the destination connection ID (a.k.a. CID) the local stack uses to identify the connection at the remote peer. Each CID is associated with a sequence number. The sequence number is transmitted in NEW_CONNECTION_ID and RETIRE_CONNECTION_ID frames to identify the CID which is being either associated with a connection or retired. The remote peer sends a NEW_CONNECTION_ID frame to let the local stack know a new CID is being associated with an existing connection. The NEW_CONNECTION_ID frame carries the new CID, its sequence number, and the retire-prior-to number. The retire-prior-to identifies existing CIDs that are to be retired. The local QUIC stack must send a RETIRE_CONNECTION_ID for every destination CID whose sequence number is less than retire-prior-to. The CID becomes retired after the local stack receives an ACK for its RETIRE_CONNECTION_ID frame. Although the OpenSSL QUIC stack supports at most one destination CID for every connection, it can be tricked into processing more than one RETIRE_CONNECTION_ID frame per connection. The OpenSSL QUIC stack currently retires the destination CID as soon as it receives the NEW_CONNECTION_ID, while in fact the destination CID must be retired after an ACK for the RETIRE_CONNECTION_ID frame is received. Correcting the flawed logic also fixes the backlog growth. [1] https://datatracker.ietf.org/doc/html/rfc9000#name-issuing-connection-ids FIPS impact: no The FIPS module is not affected as the QUIC implementation is outside of the OpenSSL FIPS module boundary.
This vulnerability carries a HIGH severity rating with a CVSS v3.1 score of 7.5, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts and availability (service disruption) for affected systems. Impacting 1 product from openssl organizations running these solutions should prioritize assessment and patching.
Reported in 2026, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.
2026-09-29T16:17:12.810
2026-10-08T01:21:22.543
Analyzed
CVSSv3.1: 7.5 (HIGH)
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Application | openssl | openssl | < 3.4.8 | Yes |
| Application | openssl | openssl | < 3.5.9 | Yes |
| Application | openssl | openssl | < 3.6.5 | Yes |
| Application | openssl | openssl | < 4.0.3 | Yes |
SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For openssl's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.