Cloudflare quiche up to 0.29.2 HEADERS set_max_field_section_size resource consumption

Summaryinfo

A vulnerability, which was classified as problematic, was found in Cloudflare quiche up to 0.29.2. The impacted element is the function set_max_field_section_size of the component HEADERS Handler. Executing a manipulation can lead to resource consumption. This vulnerability is tracked as CVE-2026-12523. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability classified as problematic was found in Cloudflare quiche up to 0.29.2. This vulnerability affects the function set_max_field_section_size of the component HEADERS Handler. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. CVE summarizes:

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. Credits: Disclosed responsibly by Sébastien Féry

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-12523 since 06/17/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1499.

Upgrading to version 0.29.3 eliminates this vulnerability.

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Productinfo

Type

• Cloud Software

Vendor

• Cloudflare

Name

• quiche

Version

• 0.29.0
• 0.29.1
• 0.29.2

Website

• Product: https://github.com/cloudflare/quiche/

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