CVE-2026-12523
7.5 · HIGHOverview
CVE-2026-12523 is a high-severity vulnerability affecting cloudflare quiche. It was published on July 14, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical Description
Summary
Cloudflare quiche's HTTP/3 layer was discovered to be vulnerable to resource exhaustion (i.e., memory) by means of specially crafted HTTP/3 frames.
Impact
HTTP/3 defines multiple frame types to support HTTP message exchanges and connection management. Each frame has a length and a payload whose length depends on the frame type. quiche was found to be vulnerable when parsing some frame types to pre-allocating memory based on the declared length. An attacker would not need to send the number of declared bytes to trigger this issue.
In addition, quiche was found to not apply QPACK decompression limits correctly. This could allow an attacker to send specially crafted HEADERS frames that would cause more memory commitment than otherwise advertised by MAX_FIELD_SECTION_SIZE (configured by set_max_field_section_size()).
Mitigation:
*
Users are requested to upgrade to quiche 0.29.3 which is the earliest version containing the fix for this issue.
Credit
Remediation
Check the references section for vendor advisories and patches from cloudflare. Update quiche to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| cloudflare | quiche | >= 0.1.0, < 0.29.3 | Affected |
Frequently Asked Questions
What is CVE-2026-12523?
CVE-2026-12523 is a high-severity vulnerability affecting cloudflare quiche. It was published on July 14, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-12523?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-12523?
Check the references section for vendor advisories and patches from cloudflare. Update quiche to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-12523?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-12523 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
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