CVE-2021-42779 [Medium] | Use-After-Free in Opensc

CVE-2021-42779 is rated Moderate Risk (48.9/100): CVSS Medium severity, with medium exploitation likelihood (EPSS 2.05%). Review affected assets and schedule remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-07-05	1.94%	2.05%	+0.11%
2	2026-06-15	0.06%	1.94%	+1.88%
3	2025-11-21	—	0.06%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-07-05

1.94%

2.05%

+0.11%

2026-06-15

0.06%

1.94%

+1.88%

2025-11-21

—

0.06%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.3	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L` 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: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:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	3.9	1.4	[email protected]
5.0	2.0	MEDIUM	`AV:N/AC:L/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: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:P) Partial availability impact.	10.0	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.3

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L 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: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:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

3.9

1.4

[email protected]

5.0

2.0

MEDIUM

AV:N/AC:L/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: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:P): Partial availability impact.

10.0

2.9

[email protected]

OS Trackers for CVE-2021-42779

vendor	priority	summary	link
`alpine`	—	CVE-2021-42779: 1 source package rows (opensc); 6 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 6.	https://security.alpinelinux.org/vuln/CVE-2021-42779
`debian`	not yet assigned	CVE-2021-42779 not yet assigned priority: Debian including 1 source packages (opensc), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2021-42779
`gentoo`	normal	CVE-2021-42779: 1 GLSA(s) (202209-03), 1 atom(s) (dev-libs/opensc); latest impact normal.	https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2021-42779
`redhat`	low	—	https://access.redhat.com/security/cve/CVE-2021-42779
`suse`	medium	CVE-2021-42779 severity moderate: SUSE including 19 source package names (libopensc2, libopensc2-32bit, …), 60 product×package rows across 49 product lines (HPE Helion OpenStack 8, SUSE CaaS Platform 4.0, … (49 product lines)): Fixed 44, Known Not Affected 16.	https://www.suse.com/security/cve/CVE-2021-42779/
`ubuntu`	medium	CVE-2021-42779 medium priority: Ubuntu including 1 source packages (opensc), 13 status rows across 13 suites (bionic, focal, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, trusty, upstream, xenial): ignored 9, not-affected 3, released 1.	https://ubuntu.com/security/CVE-2021-42779

Affected software / configurations for CVE-2021-42779

Vendor	Product	Version	Raw CPE
opensc_project	opensc	< 0.22.0	cpe:2.3:a:opensc_project:opensc::::::::
fedoraproject	fedora	33	cpe:2.3:o:fedoraproject:fedora:33:::::::*
redhat	enterprise_linux	7.0	cpe:2.3:o:redhat:enterprise_linux:7.0:::::::*
redhat	enterprise_linux	8.0	cpe:2.3:o:redhat:enterprise_linux:8.0:::::::*

References for CVE-2021-42779

URL	Tags
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=28843	Issue Tracking Mailing List Patch Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2016086	Issue Tracking Patch Third Party Advisory
https://github.com/OpenSC/OpenSC/commit/1db88374	Patch Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/06/msg00025.html
https://security.gentoo.org/glsa/202209-03	Third Party Advisory
https://lists.debian.org/debian-lts-announce/2024/12/msg00026.html

URL

CVE-2021-42779

Exploit prediction scoring system (EPSS) score for CVE-2021-42779

Common vulnerability scoring system (CVSS) metrics for CVE-2021-42779

Weakness enumeration for CVE-2021-42779

OS Trackers for CVE-2021-42779

Affected software / configurations for CVE-2021-42779

References for CVE-2021-42779