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CVE-2026-105297

HIGH 7.5

Published 2026-10-20 · Last modified 2026-10-20

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.

ELEVATED IMPACT

Severe if exploited (CVSS 7.5), but no known exploitation and low modeled probability. Patch on a normal cadence.

Exploitation likelihood

0.4%chance of exploitation in 30 days · 37th percentile

○ In CISA KEV ○ Catalogued PoC

Impact if exploited

7.5CVSS 3.1 · HIGH

  • ConfidentialityNone
  • IntegrityNone
  • AvailabilityHigh

What an attacker needs

  • ✓Access: Reachable over the network — no local access needed
  • ✓Privileges: No account or privileges required
  • ✓User interaction: No user interaction needed
  • ✓Complexity: No special conditions — reliably repeatable

✓ lowers the bar for an attacker · ⚠ raises it

Proof of concept

No public PoC is currently catalogued.

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Data snapshot:

Affected

Vendors Cloudflare

Products Https://Github.Com/Cloudflare/Pingora

Weakness (CWE)

  • CWE-770: Allocation of resources without limits or throttling

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References and research data (JSON)

Packages and version ranges

Each advisory describes its own package and affected ranges. A boundary applies to that range; it is not a universal upgrade recommendation.

  • pingora-core crates.io

    pkg:cargo/pingora-core

    SEMVER range
    • Introduced version (included): 0.0.0-0
    • Fixed boundary (excluded): 0.8.1
    Additional upstream package constraints
    {
  "ecosystem": {
    "affected_functions": null,
    "affects": {
      "arch": [],
      "functions": [],
      "os": []
    }
  },
  "database": {
    "categories": [
      "denial-of-service"
    ],
    "cvss": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
    "informational": null,
    "source": "https://github.com/rustsec/advisory-db/blob/osv/crates/RUSTSEC-2026-0389.json"
  }
}
    RustSec · RUSTSEC-2026-0389 · Updated 2026-10-26T11:15:11.357540777Z

All CVSS metrics

  • HIGH 7.5 v3.1 · CNA Primary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
  • HIGH 7.5 v3.1 · NVD Secondary
    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Advisories

Technical & other

Sources: NVD · CVE.org · EPSS