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NVD / CVE Program· CNA mitre

CVE-2021-33910: 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 strdup

Noroxi assessment

Priority: Monitor (action score 25/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 8.7% (FIRST EPSS); higher than 95.1% of all records.
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: systemd (Debian:10) 241-7~deb10u8; systemd (Debian:12) 247.3-6; systemd (Debian:9) 232-25+deb9u13.
  • Mentioned 3 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to systemd (Debian:10) 241-7~deb10u8; systemd (Debian:12) 247.3-6; systemd (Debian:9) 232-25+deb9u13 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Jul 20, 2021
Updated
Oct 14, 2026
EPSS
8.7% · 95th percentile

Report tools

JSON

Action score

25

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
3 / 30 · 8.7%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.5
CNA · mitre
5.5
agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2021-33910

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
systemd projectsystemd
fedoraprojectfedora
debiandebian linux
netapphci management node
netappsolidfire

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • debian debian linux10.0
  • fedoraproject fedora33
  • fedoraproject fedora34
  • netapp hci management nodeall versions
  • netapp solidfireall versions
  • systemd project systemd249 and later · before 249.1
  • systemd project systemd248 and later · before 248.5
  • systemd project systemd247 and later · before 247.8
  • systemd project systemdbefore 246.15

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:10systemdbefore 241-7~deb10u8241-7~deb10u8
Debian:12systemdbefore 247.3-6247.3-6
Debian:9systemdbefore 232-25+deb9u13232-25+deb9u13
openSUSE:Leap 15.2systemdbefore 234-lp152.31.31.1234-lp152.31.31.1
openSUSE:Leap 15.2systemdbefore 234-lp152.31.34.1234-lp152.31.34.1
openSUSE:Leap 15.2systemd-minibefore 234-lp152.31.34.1234-lp152.31.34.1
openSUSE:Leap 15.2systemd-minibefore 234-lp152.31.31.1234-lp152.31.31.1
openSUSE:Leap 15.3systemdbefore 234-24.90.1234-24.90.1
openSUSE:Leap 15.3systemdbefore 246.15-7.11.1246.15-7.11.1
openSUSE:Leap 15.3systemdbefore 246.13-7.8.1246.13-7.8.1
openSUSE:Leap 15.3systemdbefore 234-24.93.1234-24.93.1
openSUSE:Tumbleweedsystemdbefore 249.4-2.2249.4-2.2
Red Hat:enterprise_linux:8::baseossystemdbefore 0:239-45.el8_4.20:239-45.el8_4.2
Red Hat:enterprise_linux:8::baseossystemd-containerbefore 0:239-45.el8_4.20:239-45.el8_4.2
Red Hat:enterprise_linux:8::baseossystemd-container-debuginfobefore 0:239-45.el8_4.20:239-45.el8_4.2
Red Hat:enterprise_linux:8::baseossystemd-debuginfobefore 0:239-45.el8_4.20:239-45.el8_4.2
Red Hat:enterprise_linux:8::baseossystemd-debugsourcebefore 0:239-45.el8_4.20:239-45.el8_4.2
Red Hat:enterprise_linux:8::baseossystemd-develbefore 0:239-45.el8_4.20:239-45.el8_4.2
Red Hat:enterprise_linux:8::baseossystemd-journal-remotebefore 0:239-45.el8_4.20:239-45.el8_4.2
Red Hat:enterprise_linux:8::baseossystemd-journal-remote-debuginfobefore 0:239-45.el8_4.20:239-45.el8_4.2
Red Hat:enterprise_linux:8::baseossystemd-libsbefore 0:239-45.el8_4.20:239-45.el8_4.2
Red Hat:enterprise_linux:8::baseossystemd-libs-debuginfobefore 0:239-45.el8_4.20:239-45.el8_4.2
Red Hat:enterprise_linux:8::baseossystemd-pambefore 0:239-45.el8_4.20:239-45.el8_4.2
Red Hat:enterprise_linux:8::baseossystemd-pam-debuginfobefore 0:239-45.el8_4.20:239-45.el8_4.2

+46

Same product

systemd project: all records

Other highest-scoring records for the same primary product.

  • CVE-2017-9445In systemd through 233, certain sizes passed to dns_packet_new in systemd-resolved can cause it to allocate a buffer that's too small.
    46Plan
  • CVE-2018-21029systemd 239 through 245 accepts any certificate signed by a trusted certificate authority for DNS Over TLS.
    40Plan
  • CVE-2015-7510Stack-based buffer overflow in the getpwnam and getgrnam functions of the NSS module nss-mymachines in systemd.
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2020-13776Jun 3, 2020 · systemd through v245 mishandles numerical usernames such as ones composed of decimal digits or 0x followed by hex digits, as demonstrated by
    26Monitor
  • ← EarlierCVE-2020-13529May 10, 2021 · An exploitable denial-of-service vulnerability exists in Systemd 245.
    24Monitor
  • Later →CVE-2021-3997Aug 23, 2022 · A flaw was found in systemd.
    23Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:systemd247.3-6 · Debian:12Package registry (OSV)
opensuse:systemd234-lp152.31.31.1 · openSUSE:Leap 15.2Package registry (OSV)
opensuse:systemd-mini234-lp152.31.31.1 · openSUSE:Leap 15.2Package registry (OSV)
red hat:systemd0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:systemd-container0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:systemd-container-debuginfo0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:systemd-debuginfo0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:systemd-debugsource0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:systemd-devel0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:systemd-journal-remote0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:systemd-journal-remote-debuginfo0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:systemd-libs0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:systemd-libs-debuginfo0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:systemd-pam0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
red hat:systemd-pam-debuginfo0:239-45.el8_4.2 · Red Hat:enterprise_linux:8::baseosPackage registry (OSV)
rocky linux:systemd0:239-45.el8_4.2 · Rocky Linux:8Package registry (OSV)
suse:systemd234-24.90.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP2Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-770 · Allocation of Resources Without Limits or Throttling

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (16 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records