CVE-2023-44487: The HTTP/2 protocol allows a denial of service (server resource consumption) because request cancellation can reset many streams quickly, as
Noroxi assessment
Priority: Now (action score 90/100)
- CISA has confirmed exploitation in the wild (Oct 10, 2023). Remediation deadline for US federal agencies: Oct 31, 2023.
- Probability of exploitation in the next 30 days: 99.9% (FIRST EPSS); higher than 99.9% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: aspnetcore-runtime-6.0 (AlmaLinux:8) 6.0.23-1.el8_8; aspnetcore-runtime-7.0 (AlmaLinux:8) 7.0.12-1.el8_8; aspnetcore-targeting-pack-6.0 (AlmaLinux:8) 6.0.23-1.el8_8.
- Mentioned 3 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).
Patch today or shut off access. Upgrade to aspnetcore-runtime-6.0 (AlmaLinux:8) 6.0.23-1.el8_8; aspnetcore-runtime-7.0 (AlmaLinux:8) 7.0.12-1.el8_8; aspnetcore-targeting-pack-6.0 (AlmaLinux:8) 6.0.23-1.el8_8 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · CISA KEV · FIRST EPSS
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.
- BDU:2023-06559
- GHSA-qppj-fm5r-hxr3
- GHSA-vx74-f528-fxqg
- GHSA-xpw8-rcwv-8f8p
- ALSA-2023:5708
- ALSA-2023:5709
- ALSA-2023:5710
- ALSA-2023:5711
- ALSA-2023:5712
- ALSA-2023:5713
- ALSA-2023:5721
- ALSA-2023:5738
- ALSA-2023:5749
- ALSA-2023:5765
- ALSA-2023:5837
- ALSA-2023:5838
- ALSA-2023:5849
- ALSA-2023:5850
- ALSA-2023:5863
- ALSA-2023:5867
- Published
- Oct 10, 2023
- Updated
- Aug 11, 2026
- EPSS
- 99.9% · 99th percentile
- CWE
- CWE-400
Report tools
Action score
90
Now
Patch today or shut off access.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 30 / 30 · Listed
- EPSS
- 30 / 30 · 99.9%
CISA SSVC decision
- Exploitation
- active
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
Actively exploited in the wild
CISA added this to its Known Exploited Vulnerabilities catalog on Oct 10, 2023. That signals real attacks, not theory.
Remediation deadline for US federal agencies: Oct 31, 2023.
Get told when this record changes
- In CISA KEV: exploitation in the wild confirmed
- Weaponized exploit exists
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| siemens | simatic s7-1500 cpu 1518f-4 pn\/dp mfp firmware | cpe:2.3:o:siemens:simatic_s7-1500_cpu_1518f-4_pn\/dp_mfp_firmware |
| siemens | simatic s7-1500 cpu 1518f-4 pn\/dp mfp | cpe:2.3:h:siemens:simatic_s7-1500_cpu_1518f-4_pn\/dp_mfp |
| siemens | sinec ins | cpe:2.3:a:siemens:sinec_ins |
| siemens | sinec nms | cpe:2.3:a:siemens:sinec_nms |
| siemens | st7 scadaconnect | cpe:2.3:a:siemens:st7_scadaconnect |
| siemens | ruggedcom ape1808 firmware | cpe:2.3:o:siemens:ruggedcom_ape1808_firmware |
| siemens | ruggedcom ape1808 | cpe:2.3:h:siemens:ruggedcom_ape1808 |
| siemens | simatic s7-1500 cpu 1518-4 pn\/dp mfp firmware | cpe:2.3:o:siemens:simatic_s7-1500_cpu_1518-4_pn\/dp_mfp_firmware |
| siemens | simatic s7-1500 cpu 1518-4 pn\/dp | cpe:2.3:h:siemens:simatic_s7-1500_cpu_1518-4_pn\/dp |
| siemens | siplus s7-1500 cpu 1518-4 pn\/dp mfp firmware | cpe:2.3:o:siemens:siplus_s7-1500_cpu_1518-4_pn\/dp_mfp_firmware |
| siemens | siplus s7-1500 cpu 1518-4 pn\/dp mfp | cpe:2.3:h:siemens:siplus_s7-1500_cpu_1518-4_pn\/dp_mfp |
| redhat | ceph storage | cpe:2.3:a:redhat:ceph_storage |
and 188 more
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- f5 nginx1.9.5 and later · up to 1.25.2 inclusive
- f5 nginx plusr25 and later · before r29
- f5 nginx plusr29
- f5 nginx plusr30
- microsoft windows server 2016all versions
- microsoft windows server 2019all versions
- microsoft windows server 2022all versions
- nodejs node.js18.0.0 and later · before 18.18.2
- nodejs node.js20.0.0 and later · before 20.8.1
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| AlmaLinux:8 | aspnetcore-runtime-6.0 | before 6.0.23-1.el8_8 | 6.0.23-1.el8_8 |
| AlmaLinux:8 | aspnetcore-runtime-7.0 | before 7.0.12-1.el8_8 | 7.0.12-1.el8_8 |
| AlmaLinux:8 | aspnetcore-targeting-pack-6.0 | before 6.0.23-1.el8_8 | 6.0.23-1.el8_8 |
| AlmaLinux:8 | aspnetcore-targeting-pack-7.0 | before 7.0.12-1.el8_8 | 7.0.12-1.el8_8 |
| AlmaLinux:8 | delve | before 1.9.1-1.module_el8.8.0+3471+a62632a0 | 1.9.1-1.module_el8.8.0+3471+a62632a0 |
| AlmaLinux:8 | dotnet | before 7.0.112-1.el8_8 | 7.0.112-1.el8_8 |
| AlmaLinux:8 | dotnet-apphost-pack-6.0 | before 6.0.23-1.el8_8 | 6.0.23-1.el8_8 |
| AlmaLinux:8 | dotnet-apphost-pack-7.0 | before 7.0.12-1.el8_8 | 7.0.12-1.el8_8 |
| AlmaLinux:8 | dotnet-host | before 7.0.12-1.el8_8 | 7.0.12-1.el8_8 |
| AlmaLinux:8 | dotnet-hostfxr-6.0 | before 6.0.23-1.el8_8 | 6.0.23-1.el8_8 |
| AlmaLinux:8 | dotnet-hostfxr-7.0 | before 7.0.12-1.el8_8 | 7.0.12-1.el8_8 |
| AlmaLinux:8 | dotnet-runtime-6.0 | before 6.0.23-1.el8_8 | 6.0.23-1.el8_8 |
| AlmaLinux:8 | dotnet-runtime-7.0 | before 7.0.12-1.el8_8 | 7.0.12-1.el8_8 |
| AlmaLinux:8 | dotnet-sdk-6.0 | before 6.0.123-1.el8_8 | 6.0.123-1.el8_8 |
| AlmaLinux:8 | dotnet-sdk-6.0-source-built-artifacts | before 6.0.123-1.el8_8 | 6.0.123-1.el8_8 |
| AlmaLinux:8 | dotnet-sdk-7.0 | before 7.0.112-1.el8_8 | 7.0.112-1.el8_8 |
| AlmaLinux:8 | dotnet-sdk-7.0-source-built-artifacts | before 7.0.112-1.el8_8 | 7.0.112-1.el8_8 |
| AlmaLinux:8 | dotnet-targeting-pack-6.0 | before 6.0.23-1.el8_8 | 6.0.23-1.el8_8 |
| AlmaLinux:8 | dotnet-targeting-pack-7.0 | before 7.0.12-1.el8_8 | 7.0.12-1.el8_8 |
| AlmaLinux:8 | dotnet-templates-6.0 | before 6.0.123-1.el8_8 | 6.0.123-1.el8_8 |
| AlmaLinux:8 | dotnet-templates-7.0 | before 7.0.112-1.el8_8 | 7.0.112-1.el8_8 |
| AlmaLinux:8 | go-toolset | before 1.19.13-1.module_el8.8.0+3625+a06035cf | 1.19.13-1.module_el8.8.0+3625+a06035cf |
| AlmaLinux:8 | golang | before 1.19.13-1.module_el8.8.0+3625+a06035cf | 1.19.13-1.module_el8.8.0+3625+a06035cf |
| AlmaLinux:8 | golang-bin | before 1.19.13-1.module_el8.8.0+3625+a06035cf | 1.19.13-1.module_el8.8.0+3625+a06035cf |
+96
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| almalinux:aspnetcore-runtime-6.0 | 6.0.23-1.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:aspnetcore-runtime-7.0 | 7.0.12-1.el8_8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:aspnetcore-targeting-pack-6.0 | 6.0.23-1.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:aspnetcore-targeting-pack-7.0 | 7.0.12-1.el8_8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:dotnet | 7.0.112-1.el8_8 · AlmaLinux:8 | Package registry (OSV) |
| almalinux:dotnet-apphost-pack-6.0 | 6.0.23-1.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:dotnet-hostfxr-6.0 | 6.0.23-1.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:dotnet-runtime-6.0 | 6.0.23-1.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:dotnet-sdk-6.0 | 6.0.123-1.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:dotnet-sdk-6.0-source-built-artifacts | 6.0.123-1.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:dotnet-targeting-pack-6.0 | 6.0.23-1.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| almalinux:dotnet-templates-6.0 | 6.0.123-1.el9_2 · AlmaLinux:9 | Package registry (OSV) |
| alpine:lighttpd | 1.4.73-r0 · Alpine:v3.15 | Package registry (OSV) |
| alpine:nghttp2 | 1.46.0-r2 · Alpine:v3.15 | Package registry (OSV) |
| alpine:nginx | 1.20.2-r2 · Alpine:v3.15 | Package registry (OSV) |
| alpine:varnish | 7.3.2-r0 · Alpine:v3.17 | Package registry (OSV) |
| debian:dnsdist | 1.8.2-2 · Debian:13 | Package registry (OSV) |
| debian:h2o | 2.2.5+dfsg2-2+deb10u2 · Debian:10 | Package registry (OSV) |
| debian:haproxy | 1.8.13-1 · Debian:12 | Package registry (OSV) |
| debian:jetty9 | 9.4.50-4+deb12u2 · Debian:12 | Package registry (OSV) |
| debian:netty | 1:4.1.48-7+deb12u1 · Debian:12 | Package registry (OSV) |
| debian:nghttp2 | 1.52.0-1+deb12u1 · Debian:12 | Package registry (OSV) |
| debian:nginx | 1.24.0-2 · Debian:13 | Package registry (OSV) |
| debian:tomcat10 | 10.1.6-1+deb12u1 · Debian:12 | Package registry (OSV) |
| debian:tomcat9 | 9.0.70-2 · Debian:12 | Package registry (OSV) |
| debian:trafficserver | 9.2.3+ds-1+deb12u1 · Debian:12 | Package registry (OSV) |
| debian:varnish | 7.5.0-1 · Debian:13 | Package registry (OSV) |
| Go:github.com/nghttp2/nghttp2 | 1.57.0 | Package registry (OSV) |
| Go:golang.org/x/net | 0.17.0 | Package registry (OSV) |
| Go:google.golang.org/grpc | 1.56.3 | Package registry (OSV) |
+74
Exploit status
Weaponized
A ready exploit tool or active in-the-wild use is known for this vulnerability. This should be your top priority.
Evidence
- Exploit-DB entry ×1
- Proof-of-concept repository on GitHub ×26
Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.
| Source | Kind | Date |
|---|---|---|
| Exploit-DB entry | remote | 2025-09-16 |
| Proof-of-concept repository on GitHub | stars:248 | 2023-10-10 |
| Proof-of-concept repository on GitHub | stars:56 | 2023-10-11 |
| Proof-of-concept repository on GitHub | stars:0 | 2023-10-12 |
| Proof-of-concept repository on GitHub | stars:0 | 2023-10-12 |
| Proof-of-concept repository on GitHub | stars:76 | 2023-10-13 |
| Proof-of-concept repository on GitHub | stars:22 | 2023-10-16 |
| Proof-of-concept repository on GitHub | stars:2 | 2023-10-25 |
| Proof-of-concept repository on GitHub | stars:6 | 2023-11-08 |
| Proof-of-concept repository on GitHub | stars:15 | 2023-11-10 |
| Proof-of-concept repository on GitHub | stars:0 | 2023-12-11 |
| Proof-of-concept repository on GitHub | stars:0 | 2023-12-29 |
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
- First PoCsame day
- CISA KEVsame day
- Published
- TodayOct 28, 2026+1115 d
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
National notice (Türkiye Cybersecurity Directorate / USOM)
Official security notices citing this record; remediation advice is on the agency's page.
- TR-24-0471 · May 9, 2024(RedHat Güvenlik Güncellemesi)
- TR-23-0646 · Nov 20, 2023(SUSE Güvenlik Güncellemesi)
- TR-23-0576 · Oct 11, 2023(Windows Güvenlik Bildirimi)
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- high · the service can be disrupted
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- High
Weakness class (CWE)
CWE-400 · Uncontrolled Resource ConsumptionCVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
nvd-primary
Root cause
Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.
The bug in code
The whole CWE-400 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
function expand(node) {
return node.children.map(expand);
}Fixed
const MAX_DEPTH = 32;
function expand(node, depth = 0) {
if (depth > MAX_DEPTH) throw new Error("too deep");
return node.children.map((c) => expand(c, depth + 1));
}Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Show all references (19 more)Show less
- www.openwall.com/lists/oss-security/2023/10/10/6
- www.openwall.com/lists/oss-security/2023/10/10/7
- www.openwall.com/lists/oss-security/2023/10/13/4
- www.openwall.com/lists/oss-security/2023/10/13/9
- www.openwall.com/lists/oss-security/2023/10/18/4
- www.openwall.com/lists/oss-security/2023/10/18/8
- www.openwall.com/lists/oss-security/2023/10/19/6
- www.openwall.com/lists/oss-security/2023/10/20/8
- access.redhat.com/security/cve/cve-2023-44487
- arstechnica.com/security/2023/10/how-ddosers-used-the-http-2-protocol-to-deliver-attacks-of-unprecedented-size/
- aws.amazon.com/security/security-bulletins/AWS-2023-011/
- blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-attack/
- blog.cloudflare.com/zero-day-rapid-reset-http2-record-breaking-ddos-attack/
- blog.litespeedtech.com/2023/10/11/rapid-reset-http-2-vulnerablilty/
- blog.qualys.com/vulnerabilities-threat-research/2023/10/10/cve-2023-44487-http-2-rapid-reset-attack
- blog.vespa.ai/cve-2023-44487/
- bugzilla.proxmox.com/show_bug.cgi?id=4988
- bugzilla.redhat.com/show_bug.cgi?id=2242803
- bugzilla.suse.com/show_bug.cgi?id=1216123
Vendor advisories and official records. Exploit/PoC links are deliberately left out.