CVE-2021-34182Network attack vector

Unauthenticated command execution via writable web terminal

Published Feb 17, 2023 · Updated Mar 18, 2025

Incorrect default permissions in ttyd 1.6.3 allow remote attackers to execute commands through an exposed web terminal. The server makes credentials and read-only operation optional, so its default configuration accepts terminal input without authentication. Debian treats this behavior as intended; a network-reachable default instance exposes the configured command with the service account's privileges.

CVSS severity9.8
Critical
EPSS probability0.86%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect default permissions in ttyd 1.6.3 allow remote attackers to execute commands through an exposed web terminal. The server makes credentials and read-only operation optional, so its default configuration accepts terminal input without authentication. Debian treats this behavior as intended; a network-reachable default instance exposes the configured command with the service account's privileges.

The record

CVE
CVE-2021-34182
Published
Feb 17, 2023
Updated
Mar 18, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-276, T1059
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 17, 2023CVE publishedPublication date reported by the CVE source.
  2. Mar 18, 2025Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-276Incorrect Default Permissions
T1059Command and Scripting Interpreter

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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