CVE-2021-45931

Exp

HarfBuzz 2.9.0 has an out-of-bounds write in hb_bit_set_invertible_t::set (called from hb_sparseset_t<hb_bit_set_invertible_t>::set and hb_set_copy).

Published: 2022-01-01 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-45931 is rated High Exploit Risk (68.4/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 1.78%). 2 public exploit reference(s) are indexed (Exploit-DB). EPSS rose +1.01% over the last day, indicating growing attacker interest. 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-2021-45931

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-2021-45931

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 2026-06-15 0.77% 1.78% +1.01%
2 2025-11-21 0.74% 0.77% +0.03%
3 2025-11-18 — 0.74% —

Full EPSS history (19 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-45931

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
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:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
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.
 2.8 3.6 [email protected]
4.3 2.0 MEDIUM
AV:N/AC:M/Au:N/C:N/I:N/A:P Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:M)
Exploitation needs some favorable conditions, but not exceptional ones.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:N)
No confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:P)
Partial availability impact.
 8.6 2.9 [email protected]

Weakness enumeration for CVE-2021-45931

OS Trackers for CVE-2021-45931

vendor priority summary link
debian unimportant CVE-2021-45931 unimportant priority: Debian including 1 source packages (harfbuzz), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. https://security-tracker.debian.org/tracker/CVE-2021-45931
gentoo high CVE-2021-45931: 1 GLSA(s) (202209-11), 1 atom(s) (media-libs/harfbuzz); latest impact high. https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-45931
redhat medium — https://access.redhat.com/security/cve/CVE-2021-45931
suse high CVE-2021-45931 severity important: SUSE including 9 source package names (harfbuzz, harfbuzz-devel, …), 159 product×package rows across 41 product lines (HPE Helion OpenStack 8, SUSE CaaS Platform 4.0, … (41 product lines)): Known Not Affected 159. https://www.suse.com/security/cve/CVE-2021-45931/
ubuntu medium CVE-2021-45931 medium priority: Ubuntu including 1 source packages (harfbuzz), 8 status rows across 8 suites (bionic, focal, hirsute, impish, jammy, trusty, upstream, xenial): not-affected 7, needs-triage 1. https://ubuntu.com/security/CVE-2021-45931

Affected software / configurations for CVE-2021-45931

Vendor Product Version Raw CPE
harfbuzz_project harfbuzz 2.9.0 cpe:2.3:a:harfbuzz_project:harfbuzz:2.9.0:*:*:*:*:*:*:*
fedoraproject fedora 34 cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
fedoraproject fedora 35 cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*

References for CVE-2021-45931

cvelogic Threat Intelligence