CVE-2021-33638

Container escape via chrooted NSS library loading

Published Oct 29, 2023 · Updated Sep 9, 2024

Container escape in openEuler iSulad allows local users controlling a container to execute host code by invoking isula cp to copy files from it. The archive_chroot_tar path enters the container root filesystem while preparing an archive, allowing glibc name-service lookup to load attacker-supplied NSS libraries from that chroot. The attacker must control the source container and invoke the host-side copy operation; successful exploitation crosses the container boundary with the copy process's privileges.

CVSS severity8.4
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Container escape in openEuler iSulad allows local users controlling a container to execute host code by invoking isula cp to copy files from it. The archive_chroot_tar path enters the container root filesystem while preparing an archive, allowing glibc name-service lookup to load attacker-supplied NSS libraries from that chroot. The attacker must control the source container and invoke the host-side copy operation; successful exploitation crosses the container boundary with the copy process's privileges.

The record

CVE
CVE-2021-33638
Published
Oct 29, 2023
Updated
Sep 9, 2024
Vendor
openEuler
Product
iSulad
Classifications
CWE-665, CAPEC-480, T1611
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 29, 2023CVE publishedPublication date reported by the CVE source.
  2. Sep 9, 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=0 <=2.0.8-20210518.144540.git5288ed93,2.0.18-10,2.1.2 changes=[{"at":"0102-fix-loading-of-nsswitch-based-config-inside-chr.patch","status":"unaffected"},{"at":"0106-fix-loading-of-nsswitch-based-config-inside-chroot-u.patch","status":"unaffected"}]

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

openEuler · iSuladversion=0 <=2.0.8-20210518.144540.git5288ed93,2.0.18-10,2.1.2 changes=[{"at":"0102-fix-loading-of-nsswitch-based-config-inside-chr.patch","status":"unaffected"},{"at":"0106-fix-loading-of-nsswitch-based-config-inside-chroot-u.patch","status":"unaffected"}]

Published CVSS scores

6.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N
8.4openEulerCVSS:3.1/AV:L/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.

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-665Improper Initialization
CAPEC-480Escaping Virtualization
T1611Escape to Host

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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