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Jetty accepts "+" prefixed value in Content-Length

Moderate severity GitHub Reviewed Published Sep 14, 2023 in jetty/jetty.project • Updated Nov 6, 2023

Package

maven org.eclipse.jetty:jetty-http (Maven)

Affected versions

>= 9.0.0, <= 9.4.51
>= 10.0.0, <= 10.0.15
>= 11.0.0, <= 11.0.15
= 12.0.0

Patched versions

9.4.52
10.0.16
11.0.16
12.0.1

Description

Impact

Jetty accepts the '+' character proceeding the content-length value in a HTTP/1 header field. This is more permissive than allowed by the RFC and other servers routinely reject such requests with 400 responses. There is no known exploit scenario, but it is conceivable that request smuggling could result if jetty is used in combination with a server that does not close the connection after sending such a 400 response.

Workarounds

There is no workaround as there is no known exploit scenario.

Original Report

RFC 9110 Secion 8.6 defined the value of Content-Length header should be a string of 0-9 digits. However we found that Jetty accepts "+" prefixed Content-Length, which could lead to potential HTTP request smuggling.

Payload:

 POST / HTTP/1.1
 Host: a.com
 Content-Length: +16
 Connection: close
 ​
 0123456789abcdef

When sending this payload to Jetty, it can successfully parse and identify the length.

When sending this payload to NGINX, Apache HTTPd or other HTTP servers/parsers, they will return 400 bad request.

This behavior can lead to HTTP request smuggling and can be leveraged to bypass WAF or IDS.

References

@sbordet sbordet published to jetty/jetty.project Sep 14, 2023
Published to the GitHub Advisory Database Sep 14, 2023
Reviewed Sep 14, 2023
Published by the National Vulnerability Database Sep 15, 2023
Last updated Nov 6, 2023

Severity

Moderate

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

EPSS score

0.096%
(42nd percentile)

Weaknesses

CVE ID

CVE-2023-40167

GHSA ID

GHSA-hmr7-m48g-48f6

Source code

Credits

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