# CVE-2026-12523: Resource exhaustion in quiche HTTP/3 and QPACK layers

> CVE-2026-12523: Resource exhaustion in quiche HTTP/3 and QPACK layers. CVSS 7.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-12523
Last updated: 2026-10-24T21:10:00Z

- Published: 2026-07-14 15:51 UTC · Updated: 2026-10-24 21:10 UTC · Assigner: cloudflare
- CVSS: 7.5 (CVSS 3.1) · Severity: High · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- EPSS: 0.53%, 45th percentile (scored 2026-10-25)
- CISA KEV: no

## 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. Credits: Disclosed responsibly by Sébastien Féry

## Affected vendors and products

- Cloudflare: quiche

## Tracked companies

- [Cloudflare](https://rewindex.com/company/cloudflare.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-12523)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-12523)
- [https://github.com/cloudflare/quiche/security/advisories/GHSA-4fgf-9xrr-88gf](https://github.com/cloudflare/quiche/security/advisories/GHSA-4fgf-9xrr-88gf)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-12523 · Markdown: https://rewindex.com/cve/CVE-2026-12523.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-12523 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T04:05:25.935Z