CVE-2021-20208

Container credential access via host Kerberos cache

Published Apr 19, 2021 · Updated Aug 3, 2024

Improper privilege management in cifs-utils before 6.13 allows local users to access host Kerberos credentials from a container via a krb5 CIFS mount. The cifs.upcall helper can read credential caches visible through the host identity and use them for authenticated SMB requests when a container mounts a multiuser Kerberos share. Exploitation requires a container able to initiate that mount, and can disclose host credentials and permit unauthorized reads or writes to SMB data.

CVSS severity6.1
Medium
EPSS probability0.67%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper privilege management in cifs-utils before 6.13 allows local users to access host Kerberos credentials from a container via a krb5 CIFS mount. The cifs.upcall helper can read credential caches visible through the host identity and use them for authenticated SMB requests when a container mounts a multiuser Kerberos share. Exploitation requires a container able to initiate that mount, and can disclose host credentials and permit unauthorized reads or writes to SMB data.

The record

CVE
CVE-2021-20208
Published
Apr 19, 2021
Updated
Aug 3, 2024
Vendor
PPP Project
Product
cifs-utils
Classifications
CWE-266, CWE-269, T1552.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 19, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=cifs-utils 6.13

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

PPP Project · cifs-utilsversion=cifs-utils 6.13

Published CVSS scores

6.1NVDCVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:L/I:H/A:N

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 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-266Incorrect Privilege Assignment
CWE-269Improper Privilege Management
T1552.001Unsecured Credentials: Credentials In Files

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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