What is CVE-2023-44487?

CVE-2023-44487 is a high-severity vulnerability in Akka HTTP Server, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2023-10-10.

How severe is CVE-2023-44487?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2023-44487 known to be exploited?

Yes. CVE-2023-44487 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-10-10), indicating it is being actively exploited. 144 public proof-of-concept repositories are indexed.

Resource exhaustion in Akka HTTP Server

CVE-2023-44487

The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as exploited in the wild in August through October 2023.

Vulnerability class: DoS (Denial of Service)

Published 2023-10-10 · last modified 2026-08-11.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 1.000 (100.0th percentile), scored 2026-09-27.

Very high probability of exploitation in the next 30 days — among the top 0.1% most-likely-to-be-exploited CVEs. 100th percentile — 100.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

The 30-day trend appears once there are two daily scores.

Affected products

Weakness classification (CWE)

CWE-400 — Uncontrolled Resource Consumption

CISA KEV (Known Exploited Vulnerabilities)

This CVE is on the CISA KEV catalog, added on 2023-10-10. CISA KEV inclusion means CISA has confirmed in-the-wild exploitation; US federal agencies are required to remediate within a published due date.

BOD 22-01 due date: 2023-10-31.

Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Public proof-of-concept exploits

References

github.com/dotnet/core/blob/e4613450ea0da7fd2fc6b61dfb2c1c1dec1ce9ec/release-no… (Product, Release Notes)
blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-attack/ (Technical Description, Vendor Advisory)
aws.amazon.com/security/security-bulletins/AWS-2023-011/ (Third Party Advisory)
cloud.google.com/blog/products/identity-security/how-it-works-the-novel-http2-r… (Technical Description, Vendor Advisory)
www.nginx.com/blog/http-2-rapid-reset-attack-impacting-f5-nginx-products/ (Mitigation, Vendor Advisory)
cloud.google.com/blog/products/identity-security/google-cloud-mitigated-largest… (Technical Description, Vendor Advisory)
news.ycombinator.com/item (Issue Tracking)
blog.cloudflare.com/zero-day-rapid-reset-http2-record-breaking-ddos-attack/ (Third Party Advisory, Vendor Advisory)
www.phoronix.com/news/HTTP2-Rapid-Reset-Attack (Press/Media Coverage)
github.com/envoyproxy/envoy/pull/30055 (Patch, Issue Tracking)

Frequently asked questions

What is CVE-2023-44487?: CVE-2023-44487 is a high-severity vulnerability in Akka HTTP Server, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2023-10-10.
How severe is CVE-2023-44487?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2023-44487 known to be exploited?: Yes. CVE-2023-44487 is listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-10-10), indicating it is being actively exploited. 144 public proof-of-concept repositories are indexed.