CVE-2021-34182: An issue in ttyd v.1.6.3 allows attacker to execute arbitrary code via default configuration permissions.

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2021-34182 is a critical-severity flaw (CVSS 9.8) affecting ttyd. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue in ttyd v.1.6.3 allows attacker to execute arbitrary code via default configuration permissions.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.9% (top 41%)
CISA exploited list	No
Weakness	CWE-276
Published	2023-02-17
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: ttyd project

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

Am I affected?

Timeline

2023-02-17 18:15 UTCPublished CVE record published
2026-06-17 03:55 UTCUpdated Record last modified

ttyd project ttyd DOWNGRADE

Affected: 1.6.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.6.3

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.6.3 (Debian / Ubuntu)

apt-cache madison ttyd sudo apt install ttyd=<VERSION_BEFORE_1.6.3> sudo apt-mark hold ttyd

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

dnf --showduplicates list ttyd sudo dnf downgrade ttyd-<VERSION_BEFORE_1.6.3> sudo dnf versionlock add ttyd

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-2021-34182?

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

Is CVE-2021-34182 being exploited?

CVE-2021-34182 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-2021-34182 affect?

CVE-2021-34182 affects ttyd. Severity is critical (CVSS 9.8). An issue in ttyd v.1.6.3 allows attacker to execute arbitrary code via default configuration permissions.

How urgent is CVE-2021-34182?

Priority 59/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

References

← Back to latest CVEs