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Vulnerabilities

Vulnerability · CVE-2023-44487

HTTP/2 Rapid Reset Attack Vulnerability

Published Oct 10, 2023 · catalog updated Aug 11, 2026 · IETF HTTP/2

Patch now

CVE-2023-44487 is in the CISA known-exploited catalog, due Oct 31, 2023. Confirm IETF HTTP/2 against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Severity
High7.5
Known exploitation
CISA KEV and VulnCheck KEV
EPSS
100.00%
Remediation
Remediation guidance
Affected products
cpe ietf/http · cpe siemens/ruggedcom ape1808 firmware · cpe siemens/simatic s7-1500 cpu 1518-4 pn/dp mfp firmware · cpe siemens/simatic s7-1500 cpu 1518f-4 pn/dp mfp firmware · cpe siemens/sinec ins · cpe siemens/sinec nms

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe ietf/http2.0
  • cpe siemens/ruggedcom ape1808 firmwareversion unspecified
  • cpe siemens/simatic s7-1500 cpu 1518-4 pn/dp mfp firmwareversion unspecified
  • cpe siemens/simatic s7-1500 cpu 1518f-4 pn/dp mfp firmwareversion unspecified
  • cpe siemens/sinec insversion unspecified
  • cpe siemens/sinec ins1.0
  • cpe siemens/sinec nmsversion unspecified
  • cpe siemens/siplus s7-1500 cpu 1518-4 pn/dp mfp firmwareversion unspecified
  • vendor IETF HTTP/2version unspecified

How to fix CVE-2023-44487

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

CVE-2023-44487 is in the CISA known-exploited catalog, due Oct 31, 2023. Confirm IETF HTTP/2 against the vendor advisory and apply that fix. The CVSS score does not change the priority.

Which versions are affected?

Compare what you have installed with siemens/sinec ins 1.0. Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

What should an analyst verify?

CWE-400: Uncontrolled Resource Consumption. EPSS 100.00%. The CISA KEV listing is the exploitation evidence. A public exploit reference is linked in Sources. That is not the same as confirmed exploitation. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Oct 10, 2023 · Catalog

    Detected

    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.

  2. Oct 10, 2023 · CISA KEV

    Known exploited

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

  3. Oct 31, 2023 · CISA KEV

    Remediation due

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

  4. Aug 11, 2026 · Catalog

    Updated

    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.

Sources

  • CISA KEVConfirmed exploitationCVE-2023-44487

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

    cisa.gov
  • CVE.orgVulnerability recordCVE-2023-44487

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2023-44487

    30-day exploitation probability 100.0%

    first.org
  • Exploit DatabasePublic exploit reference52426

    Public archive entry. The exploit body is not stored here.

    exploit-db.com
  • NIST NVDVulnerability recordCVE-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.

    nvd.nist.gov
  • VulnCheck KEVConfirmed exploitationCVE-2023-44487

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

    vulncheck.com

References

Freshness

Last verified in this catalog Oct 17, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.