CVE & CISA-KEV Catalog

CVE-2019-9517

HIGHEPSS 98th pctl
7.5
CVSS v3
NVD

Description

Some HTTP/2 implementations are vulnerable to unconstrained interal data buffering, potentially leading to a denial of service. The attacker opens the HTTP/2 window so the peer can send without constraint; however, they leave the TCP window closed so the peer cannot actually write (many of) the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses, this can consume excess memory, CPU, or both.

CWE-400Resource ExhaustionCWE-770Allocation of Resources Without Limits or Throttling

How to fix

Remediation Available
mod_http2Amazon
Fixed in:0:1.15.3-2.amzn2
Fixed in:0:1.15.3-2.amzn2
Fixed in:0:1.15.3-2.amzn2
mod_http2-debuginfoAmazon
Fixed in:0:1.15.3-2.amzn2
Fixed in:0:1.15.3-2.amzn2
Fixed in:0:1.15.3-2.amzn2
apache2Debian
Fixed in:2.4.41-1CVE-2019-9517
Fixed in:2.4.41-1CVE-2019-9517
Fixed in:2.4.41-1CVE-2019-9517
apache2Ubuntu
Fixed in:2.4.18-2ubuntu3.12USN-4113-1

This Ubuntu release reached end-of-life on 2021-04-02.

Fixed in:2.4.29-1ubuntu4.10USN-4113-1

This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.

apache2-binUbuntu
Fixed in:2.4.18-2ubuntu3.12USN-4113-1

This Ubuntu release reached end-of-life on 2021-04-02.

Fixed in:2.4.29-1ubuntu4.10USN-4113-1

This Ubuntu release reached end-of-life on 2023-05-31. Extended security maintenance is available until 2028-04-01.

Node.jsWindows application
Affected:10.13.0 10.16.3Fixed in:10.16.3Node.js Foundation
Affected:12.0.0 12.8.1Fixed in:12.8.1Node.js Foundation
Affected:8.9.0 8.16.1Fixed in:8.16.1Node.js Foundation
Node.js (LTS)Windows application
Affected:12.0.0 12.8.1Fixed in:12.8.1Node.js Foundation
Affected:8.9.0 8.16.1Fixed in:8.16.1Node.js Foundation
Affected:10.13.0 10.16.3Fixed in:10.16.3Node.js Foundation
httpdWindows application
Affected:2.4.20 2.4.40Fixed in:2.4.40Apache Lounge

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Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityNone
IntegrityNone
AvailabilityHigh

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

Exploit Intelligence

27.89%probability of exploitation in 30 days
98thpercentile

Very high risk: more likely to be exploited than 98% of all known CVEs.

References

Related Vulnerabilities

Other CWE-400 (Resource Exhaustion) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2023-44487High7.5100%KEVFix
CVE-2021-44228Critical10.0100%KEV + RansomFix
CVE-2011-3192High7.899%-Fix
CVE-2019-11478Medium5.395%-Fix
CVE-2023-21547High7.589%-Fix
CVE-2018-1000115High7.588%-Fix

Common questions

How do I fix CVE-2019-9517?

Published advisories record a fix for 8 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2019-9517 being actively exploited?

Not that we know of. CVE-2019-9517 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 27.9% is the estimated probability that it will be exploited in the next 30 days. That is higher than 98% of all scored CVEs.

How severe is CVE-2019-9517?

CVE-2019-9517 has a CVSS v3 base score of 7.5, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2019-9517 affect?

Published advisories record a fix for mod_http2 (Amazon), mod_http2-debuginfo (Amazon), apache2 (Debian), apache2 (Ubuntu), and 4 more. Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-17.