CVE-2020-5303: Tendermint before versions 0.33.3, 0.32.10, and 0.31.12 has a denial-of-service vulnerability

Routine

LOW 3.1UPGRADE

CVE-2020-5303 is a low-severity flaw (CVSS 3.1) affecting tendermint. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Tendermint before versions 0.33.3, 0.32.10, and 0.31.12 has a denial-of-service vulnerability. Tendermint does not limit the number of P2P connection requests. For each p2p connection, it 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. Additionally, Tendermint

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	3.1 (Low)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.4% (top 28%)
CISA exploited list	No
Weakness	CWE-789, CWE-787
Published	2020-04-10
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: tendermint

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2020-04-10 19:15 UTCPublished CVE record published
2026-06-17 03:21 UTCUpdated Record last modified

tendermint tendermint UPGRADE

Affected: < 0.31.12 · >= 0.32.0 and < 0.32.10 · >= 0.33.0 and < 0.33.3

Fixed in: 0.31.12, 0.32.10, 0.33.3

Safe to downgrade to: a release before 0.32.0

1. Check installed version

apt-cache policy tendermint || rpm -q tendermint || tendermint --version

2. UPGRADE to 0.31.12 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade tendermint

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade tendermint

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 0.32.0 (Debian / Ubuntu)

apt-cache madison tendermint sudo apt install tendermint=<VERSION_BEFORE_0.32.0> sudo apt-mark hold tendermint

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list tendermint sudo dnf downgrade tendermint-<VERSION_BEFORE_0.32.0> sudo dnf versionlock add tendermint

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-5303?

tendermint: upgrade to 0.31.12, 0.32.10, 0.33.3. Exact commands for each OS are on this page.

Is CVE-2020-5303 being exploited?

CVE-2020-5303 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-5303 affect?

CVE-2020-5303 affects tendermint. Severity is low (CVSS 3.1). Tendermint before versions 0.33.3, 0.32.10, and 0.31.12 has a denial-of-service vulnerability. Tendermint does not limit the number of P2P connection requests. For each p2p connection, it allocates XXX bytes. Even though this memory is garb

How urgent is CVE-2020-5303?

Priority 29/100. No elevated risk signals yet.

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References

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