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go-merkledag's ProtoNode may be modified such that common method calls may panic

High severity GitHub Reviewed Published Dec 8, 2022 in ipfs/go-merkledag • Updated Feb 9, 2023

Package

gomod github.com/ipfs/go-merkledag (Go)

Affected versions

>= 0.4.0, < 0.8.1

Patched versions

0.8.1

Description

Impact

A ProtoNode may be modified in such a way as to cause various encode errors which will trigger a panic on common method calls that don't allow for error returns.

A ProtoNode should only be able to encode to valid DAG-PB, attempting to encode invalid DAG-PB forms will result in an error from the codec. Manipulation of an existing (newly created or decoded) ProtoNode using the modifier methods did not account for certain states that would place the ProtoNode into an unencodeable form.

Due to conformance with the github.com/ipfs/go-block-format#Block and github.com/ipfs/go-ipld-format#Node interfaces, certain methods, which internally require a re-encode if state has changed, will panic due to the inability to return an error.

Additionally, use of the ProtoNode#SetCidBuilder() method to set a non-functioning CidBuilder (such as one that refers to a multihash where an implementation of that hash function is not available) may cause the same methods to panic as a new CID is required but cannot be created.

Patches

Releases involving fixes for this issue are v0.8.0 and v0.8.1. The recommended minimum version is v0.8.1.

  • Additional checks are performed on ProtoNode state changes to avoid the possibility of creating unencodeable forms, errors are returned where this is the case.
  • The builder passed in to SetCidBuilder() is inspected to attempt to determine if it is usable to generate CIDs, otherwise an error is returned.
  • The panics have been removed and replaced with default values (empty byte slice for RawData() and a default zero-bytes DAG-PB CID for methods involving CIDs).

Workarounds

These workarounds are available when using impacted versions to avoid panic conditions, and may be generally appropriate in order to provide meaningful feedback to users and avoid generating bad, or unexpected encoded data:

  • Sanitise inputs when allowing user-input to set a new CidBuilder on a ProtoNode.
  • Sanitise Tsize (Link#Size) values such that they are a reasonable byte-size for sub-DAGs where derived from user-input.

References

Credit

Thanks to @mrd0ll4r for reporting the original error to Kubo!

References

@rvagg rvagg published to ipfs/go-merkledag Dec 8, 2022
Published to the GitHub Advisory Database Dec 8, 2022
Reviewed Dec 8, 2022
Published by the National Vulnerability Database Dec 8, 2022
Last updated Feb 9, 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

0.296%
(70th percentile)

CVE ID

CVE-2022-23495

GHSA ID

GHSA-x39j-h85h-3f46

Source code

Credits

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