CVE-2020-9494Network attack vector

Unauthenticated service interruption via HTTP/2 HEADERS frames

Published Jun 24, 2020 · Updated Aug 4, 2024

Resource exhaustion in affected Apache Traffic Server releases allows remote attackers to interrupt service via HTTP/2 HEADERS frames. The HTTP/2 frame-handling path accepts certain HEADERS frame patterns that drive excessive memory allocation while spinning the processing thread; Apache has not published a more specific code-level locus. No authentication or user interaction is required, but an exposed listener must accept HTTP/2; exploitation consumes memory and CPU and can make the proxy unavailable.

CVSS severity7.5
High
EPSS probability3.98%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in affected Apache Traffic Server releases allows remote attackers to interrupt service via HTTP/2 HEADERS frames. The HTTP/2 frame-handling path accepts certain HEADERS frame patterns that drive excessive memory allocation while spinning the processing thread; Apache has not published a more specific code-level locus. No authentication or user interaction is required, but an exposed listener must accept HTTP/2; exploitation consumes memory and CPU and can make the proxy unavailable.

The record

CVE
CVE-2020-9494
Published
Jun 24, 2020
Updated
Aug 4, 2024
Vendor
Apache Software Foundation
Product
Apache Traffic Server
Classifications
CWE-770, T1499.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 24, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=6.0.0 to 6.2.3
  2. Affected versionversion=7.0.0 to 7.1.10
  3. Affected versionversion=8.0.0 to 8.0.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apache Software Foundation · Apache Traffic Serverversion=6.0.0 to 6.2.3; version=7.0.0 to 7.1.10; version=8.0.0 to 8.0.7

Published CVSS scores

7.5NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
5.0NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.002Service Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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