CVE-2020-24994

HIGHNVD 8.88.8—
EchelonGraph scoreMEDIUM confidence

Score 8.8 from GitHub Security Advisory (severity: HIGH) published 2022-05-24. NVD baseline CVSS 8.8; sources differ by 0.0.

Triggered by: GitHub Security Advisory CVSS
Sources: epss, ghsa, nvd
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 3%CVSS: 8.8Exploit: None knownExposed: 0

A fix is available — apply it.

Stack overflow in the parse_tag function in libass/ass_parse.c in libass before 0.15.0 allows remote attackers to cause a denial of service or remote code execution via a crafted file.

CVSS v3
8.8
EG Score
8.8(medium)
EG Risk
45(Track)
EG Risk 45/100SSVC: Track

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity88% × 45%
Exploitation3% × 40%
Automatability30% × 15%
Action: Routine — remediate on your standard cadence.
EPSS PROB
3%
EPSS %ILE
85%
KEV
Not listed

Published

March 23, 2021

Last Modified

November 21, 2024

Advisory Details (4)

Auto-updated Aug 19, 2026
Patch available. Sources: github_commit.
generic

stack-overflow on ass_parse.c:77 mystrcmp · Issue #423 · libass/libass · GitHub

https://github.com/libass/libass/issues/423
generic

stack-overflow on ass_parse.c:234 *parse_tag · Issue #422 · libass/libass · GitHub

https://github.com/libass/libass/issues/422#issuecomment-806002919
generic

stack-overflow on ass_parse.c:234 *parse_tag · Issue #422 · libass/libass · GitHub

https://github.com/libass/libass/issues/422
github_commit Patch Available

commit 6835731c2fe4 (libass/libass)

Patch available: libass/libass 0.15.0 (contains commit 6835731c2fe4)

https://github.com/libass/libass/commit/6835731c2fe4164a0c50bc91d12c43b2a2b4e

Patch Availability(1)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntulibass5 (0.13.1-1ubuntu0.1~esm2) @ xenial2026-05-26ubuntu

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(4 across 4 ecosystems)
Debian:11(1)
PackageVulnerable rangeFixed inDependents
libass—1:0.15.0-1—
Debian:12(1)
PackageVulnerable rangeFixed inDependents
libass—1:0.15.0-1—
Debian:13(1)
PackageVulnerable rangeFixed inDependents
libass—1:0.15.0-1—
Debian:14(1)
PackageVulnerable rangeFixed inDependents
libass—1:0.15.0-1—

Weakness Classification(2)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

All Vendor Advisories

(1)

Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.

Data Freshness Timeline

(refreshed 7× in last 7d / 26× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 151 total refreshes for this CVE.

  1. 2026-09-18 19:23 UTCEPSS rescore
  2. 2026-09-17 19:22 UTCEPSS rescore
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  13. 2026-09-06 20:13 UTCOSV refresh
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  1. 2026-08-20 22:52 UTCEPSS rescore
  2. 2026-08-20 06:15 UTCOSV refresh
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  15. 2026-08-05 01:40 UTCOSV refresh
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  31. 2026-07-23 01:51 UTCEG score recompute
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  41. 2026-07-18 23:59 UTCOSV refresh
  42. 2026-07-18 10:02 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2020-24994?
CVE-2020-24994 is a high vulnerability published on March 23, 2021. Stack overflow in the parsetag function in libass/assparse.c in libass before 0.15.0 allows remote attackers to cause a denial of service or remote code execution via a crafted file.
When was CVE-2020-24994 disclosed?
CVE-2020-24994 was first published in the National Vulnerability Database on March 23, 2021, with the most recent update on November 21, 2024. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2020-24994 actively exploited?
CVE-2020-24994 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 3% probability of exploitation in the next 30 days, which ranks it in the top 15.1% of all scored CVEs.
What is the CVSS score of CVE-2020-24994?
CVE-2020-24994 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2020-24994?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2020-24994, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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