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Denial of service in Tendermint

Low severity GitHub Reviewed Published Apr 10, 2020 in tendermint/tendermint • Updated Oct 2, 2023

Package

gomod github.com/tendermint/tendermint (Go)

Affected versions

>= 0.33.0, < 0.33.3
< 0.31.12
>= 0.32.0, < 0.32.10

Patched versions

0.33.3
0.31.12
0.32.10

Description

Description

Denial of Service 1

Tendermint 0.33.2 and earlier does not limit the number of P2P connection requests. For each p2p connection, Tendermint allocates XXX bytes. Even though this memory is garbage collected once the connection is terminated (due to duplicate IP or reaching a maximum number of inbound peers), temporary memory spikes can lead to OOM (Out-Of-Memory) exceptions.

Tendermint 0.33.3 (and 0.32.10) limits the total number of P2P incoming connection requests to to p2p.max_num_inbound_peers + len(p2p.unconditional_peer_ids).

Notes:

  • Tendermint does not rate limit P2P connection requests per IP (an attacker can saturate all the inbound slots);
  • Tendermint does not rate limit HTTP(S) requests. If you expose any RPC endpoints to the public, please make sure to put in place some protection (https://www.nginx.com/blog/rate-limiting-nginx/). We may implement this in the future (tendermint/tendermint#1696).

Denial of Service 2

Tendermint 0.33.2 and earlier does not reclaim activeID of a peer after it's removed in Mempool reactor. This does not happen all the time. It only happens when a connection fails (for any reason) before the Peer is created and added to all reactors. RemovePeer is therefore called before AddPeer, which leads to always growing memory (activeIDs map). The activeIDs map has a maximum size of 65535 and the node will panic if this map reaches the maximum. An attacker can create a lot of connection attempts (exploiting Denial of Service 1), which ultimately will lead to the node panicking.

Tendermint 0.33.3 (and 0.32.10) claims activeID for a peer in InitPeer, which is executed before MConnection is started.

Notes:

  • InitPeer function was added to all reactors to combat a similar issue - tendermint/tendermint#3338;
  • Denial of Service 2 is independent of Denial of Service 1 and can be executed without it.

Specific Go Packages Affected

github.com/tendermint/tendermint/p2p

Impact

  • All full nodes (except for validators who are behind closed networks)
  • Node's memory usage increases, then it panics either in the mempool or due to OOM.

Patches

  • v0.33.3
  • v0.32.10
  • v0.31.12

Workarounds

No workarounds.

References

For more information

If you have any questions or comments about this advisory:

More information can be found here.

Credits

  • fudongbai for discovering and reporting Denial of Service 2
  • Ethan Buchman (@ebuchman) for writing a test case for Denial of Service 2 and Tess Rinearson (@tessr) for fixing it
  • Anton Kaliaev (@melekes) for fixing Denial of Service 1

References

@melekes melekes published to tendermint/tendermint Apr 10, 2020
Reviewed May 24, 2021
Published to the GitHub Advisory Database May 27, 2021
Last updated Oct 2, 2023

Severity

Low

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
High
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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:H/PR:N/UI:R/S:U/C:N/I:N/A:L

EPSS score

0.148%
(52nd percentile)

CVE ID

CVE-2020-5303

GHSA ID

GHSA-v24h-pjjv-mcp6

Source code

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