CVE-2020-21058: Cross Site Scripting vulnerability in Typora v.0.9.79 allows a remote attacker to execute arbitrary code via t

Routine

MEDIUM 6.1DOWNGRADE

CVE-2020-21058 is a medium-severity flaw (CVSS 6.1) affecting typora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Cross Site Scripting vulnerability in Typora v.0.9.79 allows a remote attacker to execute arbitrary code via the mermaid sytax.

Why this priority

Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.6% (top 53%)
CISA exploited list	No
Weakness	CWE-79
Published	2023-06-20
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: typora

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

Am I affected?

Timeline

2023-06-20 15:15 UTCPublished CVE record published
2026-06-17 03:03 UTCUpdated Record last modified

typora typora DOWNGRADE

Affected: 0.9.79

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.9.79

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.9.79 (Debian / Ubuntu)

apt-cache madison typora sudo apt install typora=<VERSION_BEFORE_0.9.79> sudo apt-mark hold typora

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list typora sudo dnf downgrade typora-<VERSION_BEFORE_0.9.79> sudo dnf versionlock add typora

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-2020-21058?

typora: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-21058 being exploited?

CVE-2020-21058 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-2020-21058 affect?

CVE-2020-21058 affects typora. Severity is medium (CVSS 6.1). Cross Site Scripting vulnerability in Typora v.0.9.79 allows a remote attacker to execute arbitrary code via the mermaid sytax.

How urgent is CVE-2020-21058?

Priority 38/100. Public exploit reference

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References

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