CVE-2021-33634

Service interruption via missing memfd re-execution

Published Oct 29, 2023 · Updated Sep 9, 2024

Improper initialization in openEuler lcr 2.0.9-6 and earlier or 2.1.2-3 and earlier allows attackers to interrupt service via a malicious image. The runtime fails to set LXC_MEMFD_REXEC before loading liblxc, leaving the host executable outside LXC's sealed-memory re-execution protection against /proc/self/exe attacks. Exploitation requires the lcr+lxc path to run the malicious image with user interaction; the recorded consequence is availability loss only.

CVSS severity6.3
Medium
EPSS probability0.20%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper initialization in openEuler lcr 2.0.9-6 and earlier or 2.1.2-3 and earlier allows attackers to interrupt service via a malicious image. The runtime fails to set LXC_MEMFD_REXEC before loading liblxc, leaving the host executable outside LXC's sealed-memory re-execution protection against /proc/self/exe attacks. Exploitation requires the lcr+lxc path to run the malicious image with user interaction; the recorded consequence is availability loss only.

The record

CVE
CVE-2021-33634
Published
Oct 29, 2023
Updated
Sep 9, 2024
Vendor
openEuler
Product
lcr
Classifications
CWE-665, CAPEC-469, T1499
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 <=2.0.9-6,2.1.2-3 changes=[{"at":"0012-265-set-env-to-avoid-invoke-lxc-binary-directly.patch","status":"unaffected"},{"at":"0008-266-set-env-to-avoid-invoke-lxc-binary-directly.patch","status":"unaffected"}]

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

openEuler · lcrversion=0 <=2.0.9-6,2.1.2-3 changes=[{"at":"0012-265-set-env-to-avoid-invoke-lxc-binary-directly.patch","status":"unaffected"},{"at":"0008-266-set-env-to-avoid-invoke-lxc-binary-directly.patch","status":"unaffected"}]

Published CVSS scores

6.3openEulerCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:N/A:H
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/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-469HTTP DoS
T1499Endpoint Denial of Service

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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