CVE-2021-33910

MEDIUMEPSS 95th pctl

5.5

CVSS v3

Description

basic/unit-name.c in systemd prior to 246.15, 247.8, 248.5, and 249.1 has a Memory Allocation with an Excessive Size Value (involving strdupa and alloca for a pathname controlled by a local attacker) that results in an operating system crash.

CWE-770Allocation of Resources Without Limits or Throttling

How to fix

Remediation Available

systemdDebian

Fixed in:247.3-6CVE-2021-33910

systemdUbuntu

Fixed in:229-4ubuntu21.31+esm1USN-5013-2

Fixed in:237-3ubuntu10.49USN-5013-1

Fixed in:245.4-4ubuntu3.10USN-5013-1

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityHigh

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

Exploit Intelligence

8.58%probability of exploitation in 30 days

95thpercentile

High risk: more likely to be exploited than 95% of all known CVEs.

References

Patch9

Exploit2

Third-Party Advisory3

Other references3

Related Vulnerabilities

Other CWE-770 (Allocation of Resources Without Limits or Throttling) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-50387	High	7.5	100%	-	Fix
CVE-2019-11478	Medium	5.3	95%	-	Fix
CVE-2019-11479	High	7.5	92%	-	Fix
CVE-2024-27316	High	7.5	91%	-	Fix
CVE-2022-30522	High	7.5	90%	-	Fix
CVE-2019-9515	High	7.5	87%	-	Fix

Common questions

How do I fix CVE-2021-33910?

Published advisories record a fix for 2 affected products. The "How to fix" section on this page lists the fixed version and source advisory for each one, so apply the entry matching what you actually run.

Is CVE-2021-33910 being actively exploited?

Not that we know of. CVE-2021-33910 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 8.6% is the estimated probability that it will be exploited in the next 30 days. That is higher than 95% of all scored CVEs.

How severe is CVE-2021-33910?

CVE-2021-33910 has a CVSS v3 base score of 5.5, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.

What does CVE-2021-33910 affect?

Published advisories record a fix for systemd (Debian), systemd (Ubuntu). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-06-09.