CVE-2021-33910

Exp

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.

Published: 2021-07-20 Last update: 2025-06-09 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-33910 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.05%). 2 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2021-33910

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2021-33910

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-05 0.04% 0.05% +0.01%
2 2026-04-01 0.10% 0.04% -0.06%
3 2025-03-30 — 0.10% —

Full EPSS history (16 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-33910

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 3.6 [email protected]
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 3.6 134c704f-9b21-4f2e-91b3-4a467353bcc0
4.9 2.0 MEDIUM
AV:L/AC:L/Au:N/C:N/I:N/A:C Click to expand
Access vector (AV:L)
Requires local access to the target system.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:C)
Complete availability impact.
 3.9 6.9 [email protected]

Weakness enumeration for CVE-2021-33910

OS Trackers for CVE-2021-33910

vendor priority summary link
debian not yet assigned CVE-2021-33910 not yet assigned priority: Debian including 1 source packages (systemd), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-33910
gentoo normal CVE-2021-33910: 1 GLSA(s) (202107-48), 1 atom(s) (sys-apps/systemd); latest impact normal. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-33910
redhat high — https://access.redhat.com/security/cve/CVE-2021-33910
suse medium CVE-2021-33910 severity moderate: SUSE including 721 source package names (0.1.0:libsystemd0-234-24.93.1, 0.1.0:libudev1-234-24.93.1, …), 1289 product×package rows across 204 product lines (Container bci/bci-init, Container bci/dotnet-aspnet, … (204 product lines)): Fixed 1140, Known Affected 136, Known Not Affected 13. https://www.suse.com/security/cve/CVE-2021-33910/
ubuntu high CVE-2021-33910 high priority: Ubuntu including 1 source packages (systemd), 9 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): released 7, needs-triage 1, not-affected 1. https://ubuntu.com/security/CVE-2021-33910

Affected software / configurations for CVE-2021-33910

Vendor Product Version Raw CPE
systemd_project systemd < 246.15 cpe:2.3:a:systemd_project:systemd:*:*:*:*:*:*:*:*
systemd_project systemd >= 247, < 247.8 cpe:2.3:a:systemd_project:systemd:*:*:*:*:*:*:*:*
systemd_project systemd >= 248, < 248.5 cpe:2.3:a:systemd_project:systemd:*:*:*:*:*:*:*:*
systemd_project systemd >= 249, < 249.1 cpe:2.3:a:systemd_project:systemd:*:*:*:*:*:*:*:*
fedoraproject fedora 33 cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
debian debian_linux 10.0 cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
netapp hci_management_node — cpe:2.3:a:netapp:hci_management_node:-:*:*:*:*:*:*:*
netapp solidfire — cpe:2.3:a:netapp:solidfire:-:*:*:*:*:*:*:*

References for CVE-2021-33910

URL Tags
http://packetstormsecurity.com/files/163621/Sequoia-A-Deep-Root-In-Linuxs-Filesystem-Layer.html Exploit Third Party Advisory VDB Entry
http://www.openwall.com/lists/oss-security/2021/08/04/2 Mailing List Patch Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/08/17/3 Mailing List Patch Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/09/07/3 Mailing List Patch Third Party Advisory
https://cert-portal.siemens.com/productcert/pdf/ssa-222547.pdf
https://github.com/systemd/systemd-stable/commit/4a1c5f34bd3e1daed4490e9d97918e504d19733b Patch Third Party Advisory
https://github.com/systemd/systemd-stable/commit/764b74113e36ac5219a4b82a05f311b5a92136ce Patch Third Party Advisory
https://github.com/systemd/systemd-stable/commit/b00674347337b7531c92fdb65590ab253bb57538 Patch Third Party Advisory
https://github.com/systemd/systemd-stable/commit/cfd14c65374027b34dbbc4f0551456c5dc2d1f61 Patch Third Party Advisory
https://github.com/systemd/systemd/commit/b34a4f0e6729de292cb3b0c03c1d48f246ad896b Patch Third Party Advisory
https://github.com/systemd/systemd/pull/20256/commits/441e0115646d54f080e5c3bb0ba477c892861ab9 Patch Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2LSDMHAKI4LGFOCSPXNVVSEWQFAVFWR7/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/42TMJVNYRY65B4QCJICBYOEIVZV3KUYI/
https://security.gentoo.org/glsa/202107-48 Third Party Advisory
https://security.netapp.com/advisory/ntap-20211104-0008/ Third Party Advisory
https://www.debian.org/security/2021/dsa-4942 Third Party Advisory
https://www.openwall.com/lists/oss-security/2021/07/20/2 Exploit Mailing List Third Party Advisory
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