CVE-2020-36429: Variant_encodeJson in open62541 1.x before 1.0.4 has an out-of-bounds write for a large recursion depth.

Routine

MEDIUM 5.5UPGRADE

CVE-2020-36429 is a medium-severity flaw (CVSS 5.5) affecting open62541. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Variant_encodeJson in open62541 1.x before 1.0.4 has an out-of-bounds write for a large recursion depth.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-787
Published	2021-07-20
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: open62541

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

Am I affected?

Timeline

2021-07-20 07:15 UTCPublished CVE record published
2026-06-17 03:15 UTCUpdated Record last modified

open62541 open62541 UPGRADE

Affected: >= 1.0.0 and < 1.0.4

Fixed in: 1.0.4

Safe to downgrade to: a release before 1.0.0

1. Check installed version

apt-cache policy open62541 || rpm -q open62541 || open62541 --version

2. UPGRADE to 1.0.4 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade open62541

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade open62541

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 1.0.0 (Debian / Ubuntu)

apt-cache madison open62541 sudo apt install open62541=<VERSION_BEFORE_1.0.0> sudo apt-mark hold open62541

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

dnf --showduplicates list open62541 sudo dnf downgrade open62541-<VERSION_BEFORE_1.0.0> sudo dnf versionlock add open62541

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-2020-36429?

open62541: upgrade to 1.0.4. Exact commands for each OS are on this page.

Is CVE-2020-36429 being exploited?

CVE-2020-36429 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-2020-36429 affect?

CVE-2020-36429 affects open62541. Severity is medium (CVSS 5.5). Variant_encodeJson in open62541 1.x before 1.0.4 has an out-of-bounds write for a large recursion depth.

How urgent is CVE-2020-36429?

Priority 25/100. No elevated risk signals yet.

Related CVEs

CVE-2022-25761 HIGH 7.5 UPGRADE MITIGATE The package open62541/open62541 before 1.2.5, from 1.3-rc1 and before 1.3.1 are vulnerable to Denial of Servic

References

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