Predictive Vulnerability Intelligence.

Product

  • Product
  • Pricing
  • Documentation

Company

  • About
  • Partnerships
  • Blog
  • Support

Legal

  • Terms
  • Privacy
  • Data Licensing

© 2026 FAUCET Technologies LLC. All rights reserved.

CVE-2021-3405

23
FAUCET Score

CVE-2021-3405 is a heap overflow vulnerability in libebml versions prior to 1.4.2, specifically impacting the EbmlString::ReadData and EbmlUnicodeString::ReadData functions. This flaw affects various distributions including Debian, Fedora, and Matroska projects utilizing libebml. Rated as MEDIUM severity (CVSS 6.5), it can be exploited remotely with low complexity, requiring user interaction, and primarily poses a high risk to availability. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.4.2CPE matchmatch criteria
cpe:2.3:a:matroska:libebml:*:*:*:*:*:*:*:*
32CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
33CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
34CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
2.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.74%
Probability of exploitation in next 30 days
EPSS Percentile
75.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0174 is in the 87th percentile among its peer group of 26,220 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

github.com / Matroska-Org/libebml/issues/74
ExploitIssue TrackingThird Party Advisory
lists.debian.org / debian-lts-announce/2021/04/msg00016.html
Third Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/JNHQI6MDOECJ2HT5GCLEX2DMJFEOWPW7
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/UHIIMWZKHHELFF4NRDMOOCS3HKK3K4DF
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/YY7R2JZRO5I6WS62KTJFTZGKYELVFTVB
security.gentoo.org / glsa/202208-21
Third Party Advisory