CVE-2020-24994: Stack overflow in the parse_tag function in libass/ass_parse.c in libass before 0.15.0 allows remote attackers

Q: How do I fix CVE-2020-24994?

libass: upgrade to 0.15.0. Exact commands for each OS are on this page.

Q: Is CVE-2020-24994 being exploited?

CVE-2020-24994 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2020-24994 affect?

CVE-2020-24994 affects libass. Severity is high (CVSS 8.8). 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.

This month

HIGH 8.8UPGRADE

CVE-2020-24994 is a high-severity flaw (CVSS 8.8) affecting libass. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	2.6% (top 14%)
CISA exploited list	No
Weakness	CWE-770
Published	2021-03-23
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: libass project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-03-23 20:15 UTCPublished CVE record published
2026-06-17 03:06 UTCUpdated Record last modified

libass project libass UPGRADE

Affected: < 0.15.0

Fixed in: 0.15.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy libass || rpm -q libass || libass --version

2. UPGRADE to 0.15.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade libass

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libass

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-24994?

libass: upgrade to 0.15.0. Exact commands for each OS are on this page.

Is CVE-2020-24994 being exploited?

CVE-2020-24994 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-24994 affect?

CVE-2020-24994 affects libass. Severity is high (CVSS 8.8). 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.

How urgent is CVE-2020-24994?

Priority 52/100. High severity

Related CVEs

CVE-2020-36430 HIGH 7.8 UPGRADE MITIGATE libass 0.15.x before 0.15.1 has a heap-based buffer overflow in decode_chars (called from decode_font and proc
CVE-2020-26682 HIGH 8.8 DOWNGRADE In libass 0.14.0, the `ass_outline_construct`'s call to `outline_stroke` causes a signed integer overflow.
CVE-2016-7972 HIGH 7.5 MITIGATE MITIGATE The check_allocations function in libass/ass_shaper.c in libass before 0.13.4 allows remote attackers to cause
CVE-2016-7970 HIGH 7.5 MITIGATE UPGRADE Buffer overflow in the calc_coeff function in libass/ass_blur.c in libass before 0.13.4 allows remote attacker
CVE-2016-7969 HIGH 7.5 MITIGATE MITIGATE The wrap_lines_smart function in ass_render.c in libass before 0.13.4 allows remote attackers to cause a denia

References

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