CVE-2023-44487: HTTP/2 Rapid Reset Attack Vulnerability

Q: How do I fix CVE-2023-44487?

simatic s7-1500 cpu 1518f-4 pn\/dp mfp firmware: mitigate or apply the listed mitigation; sinec ins: upgrade to 1.0; sinec nms: upgrade to 3.0. Exact commands for each OS are on this page.

Q: Is CVE-2023-44487 being exploited?

Yes. CVE-2023-44487 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

Q: What does CVE-2023-44487 affect?

CVE-2023-44487 affects simatic s7-1500 cpu 1518f-4 pn\/dp mfp firmware, sinec ins, sinec nms. Severity is high (CVSS 7.5). 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.

Q: How urgent is CVE-2023-44487?

Priority 86/100. High severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference; Remotely exploitable, no login, no user action

Patch now

HIGH 7.5EXPLOITEDREMOTEMITIGATEUPGRADEUPGRADE

CVE-2023-44487 is a high-severity flaw (CVSS 7.5) affecting simatic s7-1500 cpu 1518f-4 pn\/dp mfp firmware, sinec ins, sinec nms, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity
EPSS top 1%: very likely to be exploited
Exploited in the wild (CISA KEV)
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	100.0% (top 1%)
CISA exploited list	Yes, fix due 2023-10-31
Weakness	CWE-400
Published	2023-10-10
Last modified	2026-08-11

Publisher (CNA): MITRE · Vendor: siemens

Last updated 2026-08-11 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-10-10Exploited Added to the CISA Known Exploited Vulnerabilities list
2023-10-10 14:15 UTCPublished CVE record published
2023-10-31Deadline CISA due date for US federal agencies to patch
2026-08-11 19:37 UTCUpdated Record last modified

siemens simatic s7-1500 cpu 1518f-4 pn\/dp mfp firmware MITIGATE

Affected: >= 3.1.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.1.5

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

siemens sinec ins UPGRADE

Affected: < 1.0 · 1.0 · 1.0 sp1 · 1.0 sp2 · 1.0 sp2_update_1 · 1.0 sp2_update_2

Fixed in: 1.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy sinec-ins || rpm -q sinec-ins || sinec-ins --version

2. UPGRADE to 1.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade sinec-ins

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade sinec-ins

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

siemens sinec nms UPGRADE

Affected: < 3.0

Fixed in: 3.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy sinec-nms || rpm -q sinec-nms || sinec-nms --version

2. UPGRADE to 3.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade sinec-nms

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade sinec-nms

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

siemens st7 scadaconnect UPGRADE

Affected: < 1.1

Fixed in: 1.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy st7-scadaconnect || rpm -q st7-scadaconnect || st7-scadaconnect --version

2. UPGRADE to 1.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade st7-scadaconnect

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade st7-scadaconnect

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

siemens ruggedcom ape1808 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

siemens simatic s7-1500 cpu 1518-4 pn\/dp mfp firmware MITIGATE

Affected: >= 3.1.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.1.5

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Go · golang.org/x/net · FIXED · 0.17.0 · vulnerable: < 0.17.0 · source

go get golang.org/x/net@v0.17.0 go list -m golang.org/x/net

Maven · org.apache.tomcat.embed:tomcat-embed-core · FIXED · 11.0.0-M12 · vulnerable: >= 11.0.0-M1, < 11.0.0-M12 · source

Set org.apache.tomcat.embed:tomcat-embed-core to 11.0.0-M12 or later in pom.xml or build.gradle, then rebuild and redeploy.

Maven · org.eclipse.jetty.http2:http2-common · FIXED · 9.4.53 · vulnerable: >= 9.3.0, < 9.4.53 · source

Set org.eclipse.jetty.http2:http2-common to 9.4.53 or later in pom.xml or build.gradle, then rebuild and redeploy.

Fedora ELN · libmamba · FIXED · 2.10.0-1.eln159 · FEDORA-2026-cc57be9e65 · source

sudo dnf upgrade --advisory=FEDORA-2026-cc57be9e65

Fedora 46 · rubygem-selenium-webdriver · FIXED · 4.34.0-5.fc46 · FEDORA-2026-111c6e6363 · source

sudo dnf upgrade --advisory=FEDORA-2026-111c6e6363

Ubuntu 20.04 · haproxy · NOT AFFECTED

Ubuntu 22.04 · haproxy · NOT AFFECTED

Ubuntu 24.04 · haproxy · NOT AFFECTED

Ubuntu 24.10 · haproxy · NOT AFFECTED

Ubuntu 25.04 · haproxy · NOT AFFECTED

Debian 12 · dnsdist · NO FIX YET

Debian 13 · dnsdist · FIXED · 1.8.2-2

sudo apt update && sudo apt install --only-upgrade dnsdist dpkg --compare-versions "$(dpkg-query -W -f='${Version}' dnsdist)" ge "1.8.2-2" && echo PATCHED || echo STILL-VULNERABLE

Debian 12 · grpc · NO FIX YET

Debian 13 · grpc · NO FIX YET

RHEL 10 · tomcat · FIXED · tomcat-10.1.36-1.el10_0

sudo dnf upgrade --advisory=RHSA-2025:7497 rpm -q tomcat

RHEL 7 · rhc-worker-script · FIXED · rhc-worker-script-0.5-1.el7_9

sudo dnf upgrade --advisory=RHSA-2023:5835 rpm -q rhc-worker-script

RHEL 8 · dotnet7.0 · FIXED · dotnet7.0-7.0.112-1.el8_8

sudo dnf upgrade --advisory=RHSA-2023:5709 rpm -q dotnet7.0

RHEL 8 · dotnet6.0 · FIXED · dotnet6.0-6.0.123-1.el8_8

sudo dnf upgrade --advisory=RHSA-2023:5710 rpm -q dotnet6.0

RHEL 8 · grafana · FIXED · grafana-7.5.15-5.el8_8

sudo dnf upgrade --advisory=RHSA-2023:5863 rpm -q grafana

Alpine 3.20 · nghttp2 · FIXED · nghttp2-1.57.0-r0

apk add --upgrade nghttp2 apk info -v nghttp2

Alpine 3.20 · nginx · FIXED · nginx-1.24.0-r12

apk add --upgrade nginx apk info -v nginx

Alpine 3.20 · nodejs · NOT AFFECTED

Alpine 3.20 · varnish · FIXED · varnish-7.4.2-r0

apk add --upgrade varnish apk info -v varnish

Amazon Linux 2023 · see advisory · FIXED · ALAS2023-2024-474 · source

sudo dnf update --advisory=ALAS2023-2024-474

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: bcdannyboy/CVE-2023-44487 (248 stars)
GitHub PoC: secengjeff/rapidresetclient (76 stars)
GitHub PoC: imabee101/CVE-2023-44487 (56 stars)
Write-up: blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-attack/
Write-up: blog.cloudflare.com/zero-day-rapid-reset-http2-record-breaking-ddos-attack/
Write-up: cert-portal.siemens.com/productcert/html/ssa-082556.html
GitHub PoC: BMG-Black-Magic/CVE-2023-44487
Exploit-DB: HTTP/2 2.0 - Denial Of Service (DOS)

Advisories and coverage

Official advisories

GitLab Security Releases: GitLab Security Release: 16.5.1, 16.4.2, 16.3.6 2023-10-31

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2023-44487?

simatic s7-1500 cpu 1518f-4 pn\/dp mfp firmware: mitigate or apply the listed mitigation; sinec ins: upgrade to 1.0; sinec nms: upgrade to 3.0. Exact commands for each OS are on this page.

Is CVE-2023-44487 being exploited?

Yes. CVE-2023-44487 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2023-44487 affect?

CVE-2023-44487 affects simatic s7-1500 cpu 1518f-4 pn\/dp mfp firmware, sinec ins, sinec nms. Severity is high (CVSS 7.5). 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.

How urgent is CVE-2023-44487?

Priority 86/100. High severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Siemens vulnerabilities

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References

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