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CVE-2021-33910VulnerabilityPublished Updated

CVE-2021-33910: n/a

Source CVE Database V5

0

Not known to be exploited · CVSS 5.5 Medium : upgrade to 246.15 when convenient.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
8.7% chance of exploitation in 30 days – higher than 95% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 246.15
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 20 Jul 2021

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-26.

What to do

Upgrade systemd/systemd to 246.15.

Affected software

ProductAffectedFixed in
GitHubsystemd/systemdpkg:github/systemd/systemdOther threatsAffected
  • <246.15
  • =247.8
  • =248.5
  • =249.1
Fixed in
  • 246.15

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2021-33910, European organizations should: 1) Ensure systemd is updated to versions 246.15, 247.8, 248.5, 249.1 or later, where the vulnerability is fixed. Regular patch management processes should prioritize these updates. 2) Restrict local access to trusted users only, employing strict access controls and monitoring to reduce the risk of local exploitation. 3) Implement system hardening measures such as limiting the length of pathnames or input strings where possible, and applying resource limits (ulimits) to prevent excessive stack usage by processes. 4) Deploy intrusion detection and prevention systems to monitor for unusual local activity that could indicate exploitation attempts. 5) Use containerization or sandboxing to isolate critical services, limiting the impact of any local denial of service. 6) Maintain robust backup and recovery procedures to minimize downtime in case of crashes. 7) Educate system administrators and users about the risks of local privilege misuse and enforce the principle of least privilege. These steps go beyond generic advice by focusing on controlling local access vectors, applying resource constraints, and ensuring timely patching of systemd components.

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.

References

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