CVE-2020-1944Public exploitNetwork attack vector

Unauthenticated request smuggling via conflicting length headers

Published Mar 23, 2020 · Updated Aug 4, 2024

HTTP request smuggling in Apache Traffic Server allows remote attackers to desynchronize proxy and origin HTTP message boundaries. The HTTP/1.1 request-framing path accepts conflicting Transfer-Encoding and Content-Length headers, so downstream software can assign a different length to the same request. No authentication or user interaction is required; a crafted message can conceal another request and expose or alter traffic on a reused back-end connection.

CVSS severity9.8
Critical
EPSS probability2.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

HTTP request smuggling in Apache Traffic Server allows remote attackers to desynchronize proxy and origin HTTP message boundaries. The HTTP/1.1 request-framing path accepts conflicting Transfer-Encoding and Content-Length headers, so downstream software can assign a different length to the same request. No authentication or user interaction is required; a crafted message can conceal another request and expose or alter traffic on a reused back-end connection.

The record

CVE
CVE-2020-1944
Published
Mar 23, 2020
Updated
Aug 4, 2024
Vendor
The Apache Software Foundation
Product
Apache Traffic Server
Classifications
CWE-444, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 23, 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=Apache Traffic Server 6.0.0 to 6.2.3, 7.0.0 to 7.1.8, and 8.0.0 to 8.0.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Traffic Serverversion=Apache Traffic Server 6.0.0 to 6.2.3, 7.0.0 to 7.1.8, and 8.0.0 to 8.0.5

Published CVSS scores

7.5NIST National Vulnerability DatabaseAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 exploitPublished

Weakness, pattern, technique

CWE-444Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
T1190Exploit Public-Facing Application

Public exploit references

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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