Description
Summary



Cloudflare quiche was discovered to be vulnerable to memory resource exhaustion due to unbounded queuing of post-handshake client migration events.



Impact



quiche supports the connection migration features described in Section 9 of RFC 9000, which allows a single QUIC connection to survive changes in the network path. Although quiche implements the protections described in Section 9.3 of RFC 9000 to limit server state commitment, it was discovered that the collection of PathEvents, intended to be consumed by applications via the path_event_next() function, was not bounded.



Once the QUIC handshake completed, a peer could exploit rapid source address migration in order to cause unbounded queuing of the PathEvent::ReusedSourceConnectionId type. Servers are vulnerable even if active connection migration is disabled.



Mitigation:

*

Applications can call path_event_next() to drain the PathEvent collection, mitigating the attack.


*

Users are requested to upgrade to quiche 0.29.3 which is the earliest version that prevents excessive queueing of PathEvent::ReusedSourceConnectionId.
Published: 2026-07-14
Score: 7.5 High
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Impact

Cloudflare quiche contains an unbounded queue for PathEvent::ReusedSourceConnectionId events that is intended to be processed by the application through the path_event_next() function. This represents a Resource Exhaustion flaw (CWE‑770) where rapid source address migration after the QUIC handshake can cause the queue to grow without limit, consuming server memory. If the process exhausts available memory, it can experience degradation or a service outage, representing a denial of service via resource exhaustion.

Affected Systems

The vulnerability affects Cloudflare quiche implementations deployed before version 0.29.3. Any environment that uses quiche to handle QUIC connections and allows source address migration is potentially impacted, regardless of whether migration is enabled.

Risk and Exploitability

The CVSS score of 7.5 indicates high severity. The EPSS score is reported as less than 1 %, indicating a very low but non‑zero exploitation probability. The CVE is not listed in the CISA KEV catalog. Attackers require network access to a QUIC endpoint and would trigger rapid source address migrations to overflow the queue. While active exploitation appears unlikely, the potential for memory exhaustion and service disruption warrants prompt remediation.

Generated by OpenCVE AI on July 31, 2026 at 10:10 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Upgrade Cloudflare quiche to version 0.29.3 or later, which limits PathEvent::ReusedSourceConnectionId queue growth.
  • If an upgrade is delayed, ensure the application calls path_event_next() frequently to drain queued events.
  • Consider disabling or restricting source address migration at the QUIC stack level to reduce event generation.
  • Monitor memory usage for abnormal growth that may indicate exploitation attempts.

Generated by OpenCVE AI on July 31, 2026 at 10:10 UTC.

Tracking

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Advisories

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History

Tue, 14 Jul 2026 17:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 14 Jul 2026 17:00:00 +0000

Type Values Removed Values Added
First Time appeared Cloudflare
Cloudflare quiche
Vendors & Products Cloudflare
Cloudflare quiche

Tue, 14 Jul 2026 15:45:00 +0000

Type Values Removed Values Added
Description Summary Cloudflare quiche was discovered to be vulnerable to memory resource exhaustion due to unbounded queuing of post-handshake client migration events. Impact quiche supports the connection migration features described in Section 9 of RFC 9000, which allows a single QUIC connection to survive changes in the network path. Although quiche implements the protections described in Section 9.3 of RFC 9000 to limit server state commitment, it was discovered that the collection of PathEvents, intended to be consumed by applications via the path_event_next() function, was not bounded. Once the QUIC handshake completed, a peer could exploit rapid source address migration in order to cause unbounded queuing of the PathEvent::ReusedSourceConnectionId type. Servers are vulnerable even if active connection migration is disabled. Mitigation: * Applications can call path_event_next() to drain the PathEvent collection, mitigating the attack. * Users are requested to upgrade to quiche 0.29.3 which is the earliest version that prevents excessive queueing of PathEvent::ReusedSourceConnectionId.
Title Unbounded path event queue growth in quiche via peer-driven source connection ID rotation
Weaknesses CWE-770
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

Subscriptions

Cloudflare Quiche
cve-icon MITRE

Status: PUBLISHED

Assigner: cloudflare

Published:

Updated: 2026-07-14T15:57:47.140Z

Reserved: 2026-06-19T10:27:48.087Z

Link: CVE-2026-12707

cve-icon Vulnrichment

Updated: 2026-07-14T15:57:43.252Z

cve-icon NVD

No data.

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-07-31T10:15:06Z

Weaknesses
  • CWE-770

    Allocation of Resources Without Limits or Throttling