CVE-2021-44512

Session hijacking via world-writable socket directory

Published Dec 7, 2021 · Updated Aug 4, 2024

Incorrect permissions in tmate-ssh-server 2.3.0 allow local users to hijack sessions or disclose read-write session tokens. The /tmp/tmate/sessions directory is world-writable, permitting attacker-controlled UNIX sockets, while readlink() reveals targets of read-only session symlinks. A local account can redirect session handling; knowledge of a read-only token also enables recovery of the linked read-write token and full session access.

CVSS severity7.0
High
EPSS probability0.25%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect permissions in tmate-ssh-server 2.3.0 allow local users to hijack sessions or disclose read-write session tokens. The /tmp/tmate/sessions directory is world-writable, permitting attacker-controlled UNIX sockets, while readlink() reveals targets of read-only session symlinks. A local account can redirect session handling; knowledge of a read-only token also enables recovery of the linked read-write token and full session access.

The record

CVE
CVE-2021-44512
Published
Dec 7, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-732, T1552.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 7, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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 vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.0NIST NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
4.4NIST NVDAV:L/AC:M/Au:N/C:P/I:P/A:P

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-732Incorrect Permission Assignment for Critical Resource
T1552.001Unsecured Credentials: Credentials In Files

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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