CVE-2023-44487

KEVHTTP/2 Rapid Reset Attack Vulnerability

Description

HTTP/2 contains a rapid reset vulnerability that allows for a distributed denial-of-service attack (DDoS).

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.

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

PublishedOct 10, 2023

Last modifiedAug 11, 2026

Added to KEVOct 10, 2023

Remediation dueOct 31, 2023

References

openwall.com/lists/oss-security/2023/10/10/6Mailing ListThird Party Advisory
openwall.com/lists/oss-security/2023/10/10/7Mailing ListThird Party Advisory
openwall.com/lists/oss-security/2023/10/13/4Mailing ListThird Party Advisory
openwall.com/lists/oss-security/2023/10/13/9Mailing ListThird Party Advisory
openwall.com/lists/oss-security/2023/10/18/4Mailing ListThird Party Advisory
openwall.com/lists/oss-security/2023/10/18/8Mailing ListThird Party Advisory
openwall.com/lists/oss-security/2023/10/19/6Mailing ListThird Party Advisory
openwall.com/lists/oss-security/2023/10/20/8Mailing ListThird Party Advisory
access.redhat.com/security/cve/cve-2023-44487Vendor Advisory
arstechnica.com/security/2023/10/how-ddosers-used-the-http-2-protocol-to-deliver-attacks-of-unprecedented-size/Press/Media CoverageThird Party Advisory
aws.amazon.com/security/security-bulletins/AWS-2023-011/Third Party Advisory
blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-attack/Technical DescriptionVendor Advisory

0 recent articles mention this CVE

Risk assessment · High

Actively exploited. Patch immediately.

Exploitation: Confirmed in the wild (CISA KEV)
Federal remediation deadline: Overdue by 1091 days
CVSS: 7.5 HIGH
EPSS (30-day exploit probability): 100.0% · top 1% of all CVEs
Weakness: NVD-CWE-noinfo
Attack vector: Network, remotely reachable
Preconditions: No privileges and no user interaction

Recommended actions

1.Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
2.Treat as emergency change: patch or isolate internet-facing instances first.
3.Review exposure: confirm which instances are reachable from the internet and restrict access until patched.
4.Hunt for compromise: review logs for the disclosure window, not just from the patch date.

Assessment is derived automatically from the live signals above; verify against your own asset inventory.