CVE-2020-36430 [High] | Out-of-bounds Write in Libass

CVE-2020-36430 is rated Moderate Risk (53.1/100): CVSS High severity, with medium exploitation likelihood (EPSS 1.07%). Review affected assets and schedule remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.31%	1.07%	+0.76%
2	2025-12-10	0.38%	0.31%	-0.07%
3	2025-11-21	—	0.38%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.31%

1.07%

+0.76%

2025-12-10

0.38%

0.31%

-0.07%

2025-11-21

—

0.38%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.8	3.1	HIGH	`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/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: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:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	5.9	[email protected]
6.8	2.0	MEDIUM	`AV:N/AC:M/Au:N/C:P/I:P/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:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	8.6	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.8

3.1

HIGH

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/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: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:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

5.9

[email protected]

6.8

2.0

MEDIUM

AV:N/AC:M/Au:N/C:P/I:P/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:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

8.6

6.4

[email protected]

OS Trackers for CVE-2020-36430

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2020-36430 not yet assigned priority: Debian including 1 source packages (libass), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2020-36430
`gentoo`	low	CVE-2020-36430: 1 GLSA(s) (202208-13), 1 atom(s) (media-libs/libass); latest impact low.	https://bugs.gentoo.org/buglist.cgi?quicksearch=CVE-2020-36430
`suse`	high	CVE-2020-36430 severity important: SUSE including 9 source package names (0.3.32-3.4:libass9-0.14.0-3.9.1, libass, …), 83 product×package rows across 45 product lines (Container containers/open-webui, HPE Helion OpenStack 8, … (45 product lines)): Fixed 52, Known Not Affected 31.	https://www.suse.com/security/cve/CVE-2020-36430/
`ubuntu`	medium	CVE-2020-36430 medium priority: Ubuntu including 1 source packages (libass), 9 status rows across 9 suites (bionic, focal, groovy, hirsute, impish, jammy, trusty, upstream, xenial): not-affected 6, ignored 2, released 1.	https://ubuntu.com/security/CVE-2020-36430

Affected software / configurations for CVE-2020-36430

Vendor	Product	Version	Raw CPE
libass_project	libass	>= 0.15.0, < 0.15.1	cpe:2.3:a:libass_project:libass::::::::
fedoraproject	fedora	34	cpe:2.3:o:fedoraproject:fedora:34:::::::*

References for CVE-2020-36430

URL	Tags
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=26674	Issue Tracking Patch Third Party Advisory
https://github.com/google/oss-fuzz-vulns/blob/main/vulns/libass/OSV-2020-2099.yaml	Third Party Advisory
https://github.com/libass/libass/commit/017137471d0043e0321e377ed8da48e45a3ec632	Patch Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6JUXFQUJ32GWG5E46A63DFDCYJAF3VU6/
https://security.gentoo.org/glsa/202208-13	Third Party Advisory

URL

CVE-2020-36430

Exploit prediction scoring system (EPSS) score for CVE-2020-36430

Common vulnerability scoring system (CVSS) metrics for CVE-2020-36430

Weakness enumeration for CVE-2020-36430

OS Trackers for CVE-2020-36430

Affected software / configurations for CVE-2020-36430

References for CVE-2020-36430