CVE-2020-24994 [High] | Denial of Service in Libass

CVE-2020-24994 is rated High Risk (65.5/100): CVSS High severity, with medium exploitation likelihood (EPSS 2.63%). EPSS rose +1.05% over the last day, indicating growing attacker interest. High exploitation likelihood—assess exposure and prioritize remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	1.58%	2.63%	+1.05%
2	2025-11-21	1.51%	1.58%	+0.07%
3	2025-11-18	—	1.51%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

1.58%

2.63%

+1.05%

2025-11-21

1.51%

1.58%

+0.07%

2025-11-18

—

1.51%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
8.8	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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: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.	2.8	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

8.8

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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: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.

2.8

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-2020-24994

vendor	priority	summary	link
`alpine`	high	CVE-2020-24994: 1 source package rows (libass); 2 state rows across 2 repos (3.22-community, edge-community); fixed 0, open 2.	https://security.alpinelinux.org/vuln/CVE-2020-24994
`debian`	not yet assigned	CVE-2020-24994 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-2020-24994
`suse`	medium	CVE-2020-24994 severity moderate: SUSE including 10 source package names (0.3.32-3.4:libass9-0.14.0-3.6.1, libass, …), 43 product×package rows across 25 product lines (Container containers/open-webui, SUSE Linux Enterprise High Performance Computing 12 SP5, … (25 product lines)): Fixed 24, Will Not Fix 19.	https://www.suse.com/security/cve/CVE-2020-24994/
`ubuntu`	medium	CVE-2020-24994 medium priority: Ubuntu including 1 source packages (libass), 16 status rows across 16 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, mantic, noble, oracular, plucky, questing, trusty, upstream, xenial): not-affected 10, needed 3, released 2, ignored 1.	https://ubuntu.com/security/CVE-2020-24994

Affected software / configurations for CVE-2020-24994

Vendor	Product	Version	Raw CPE
libass_project	libass	< 0.15.0	cpe:2.3:a:libass_project:libass::::::::

References for CVE-2020-24994

URL	Tags
https://github.com/libass/libass/commit/6835731c2fe4164a0c50bc91d12c43b2a2b4e	Patch Third Party Advisory
https://github.com/libass/libass/issues/422	Patch Third Party Advisory
https://github.com/libass/libass/issues/422#issuecomment-806002919	Issue Tracking Patch Third Party Advisory
https://github.com/libass/libass/issues/423	Third Party Advisory

URL

CVE-2020-24994

Exploit prediction scoring system (EPSS) score for CVE-2020-24994

Common vulnerability scoring system (CVSS) metrics for CVE-2020-24994

Weakness enumeration for CVE-2020-24994

OS Trackers for CVE-2020-24994

Affected software / configurations for CVE-2020-24994

References for CVE-2020-24994