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SnappyFrameDecoder doesn't restrict chunk length any may buffer skippable chunks in an unnecessary way

High severity GitHub Reviewed Published Sep 9, 2021 in netty/netty • Updated Aug 16, 2023

Package

maven io.netty:netty (Maven)

Affected versions

< 4.0.0

Patched versions

None
maven io.netty:netty-codec (Maven)
>= 4.0.0, < 4.1.68.Final
4.1.68.Final
maven org.jboss.netty:netty (Maven)
< 4.0.0
None

Description

Impact

The Snappy frame decoder function doesn't restrict the chunk length which may lead to excessive memory usage. Beside this it also may buffer reserved skippable chunks until the whole chunk was received which may lead to excessive memory usage as well.

This vulnerability can be triggered by supplying malicious input that decompresses to a very big size (via a network stream or a file) or by sending a huge skippable chunk.

Impact

All users of SnappyFrameDecoder are affected and so the application may be in risk for a DoS attach due excessive memory usage.

References

https://github.com/netty/netty/blob/netty-4.1.67.Final/codec/src/main/java/io/netty/handler/codec/compression/SnappyFrameDecoder.java#L79
https://github.com/netty/netty/blob/netty-4.1.67.Final/codec/src/main/java/io/netty/handler/codec/compression/SnappyFrameDecoder.java#L171
https://github.com/netty/netty/blob/netty-4.1.67.Final/codec/src/main/java/io/netty/handler/codec/compression/SnappyFrameDecoder.java#L185

References

@normanmaurer normanmaurer published to netty/netty Sep 9, 2021
Reviewed Sep 9, 2021
Published to the GitHub Advisory Database Sep 9, 2021
Published by the National Vulnerability Database Oct 19, 2021
Last updated Aug 16, 2023

Severity

High

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
None
Availability
High

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:N/A:H

EPSS score

1.049%
(85th percentile)

Weaknesses

CVE ID

CVE-2021-37137

GHSA ID

GHSA-9vjp-v76f-g363

Source code

Credits

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