# CVE-2026-105297: Pingora HTTP/2 server memory exhaustion through unbounded default header-list and concurrent-stream limits

> CVE-2026-105297: Pingora HTTP/2 server memory exhaustion through unbounded default header-list and concurrent-stream limits. CVSS 7.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-105297
Last updated: 2026-10-20T20:17:11Z

- Published: 2026-10-20 00:40 UTC · Updated: 2026-10-20 20:17 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: 0.43%, 37th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-770

## Description

Summary Before version 0.8.1, Pingora's HTTP/2 server used the h2 crate's default limits unless the application set its own 16 MiB decoded header-list size and no limit on concurrent streams. A remote, unauthenticated client can send 1-byte HPACK references to a near-empty header, making the server allocate hundreds of thousands of header fields per stream across an unlimited number of streams on one connection, and use HTTP/2 flow control to keep those streams open. This can exhaust memory and degrade or terminate the Pingora process. Impact Remote, unauthenticated denial of service against any Pingora service that terminates HTTP/2 (h2 or h2c) without explicitly setting max\_header\_list\_size and max\_concurrent\_streams. The reporter showed that a single connection could get a Pingora process with a 2 GiB memory limit OOM-killed. Note that Cloudflare CDN customers were unaffected, as internal Pingora services at Cloudflare do not have HTTP/2 clients. Mitigation:   \*   Upgrade to pingora 0.8.1 or later (fix:  https://github.com/cloudflare/pingora/commit/d193c8d49b8b7c1c1ede93183759caa4f6906bbd ). When no H2Options are supplied, Pingora now advertises and enforces a 64 KiB decoded header-list limit and at most 100 concurrent streams per connection.   \*   Applications that supply their own H2Options are not covered by these defaults and must set max\_header\_list\_size and max\_concurrent\_streams explicitly (this also works on versions before 0.8.1), or, on 0.8.1 and later, start from pingora\_core::protocols::http::v2::server::default\_h2\_options(). H2Options::default() does not include these limits.

## Affected vendors and products

- Cloudflare: https://github.com/cloudflare/pingora

## Tracked companies

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

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-105297)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-105297)
- [https://github.com/cloudflare/pingora](https://github.com/cloudflare/pingora)

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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-2026-105297 · Markdown: https://rewindex.com/cve/CVE-2026-105297.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-105297 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:13:33.423Z