HOMEVULNERABILITIESCVE-2021-3403
HIGH

CVE-2021-3403

CWE-416Published: March 4, 2021· Updated: Jun 17, 2026

7.8
CVSS v3.1

Official Description

In ytnef 1.9.3, the TNEFSubjectHandler function in lib/ytnef.c allows remote attackers to cause a denial-of-service (and potentially code execution) due to a double free which can be triggered via a crafted file.

NVD Source

Technical Analysis

CVE-2021-3403 requires local access, meaning attackers must already have a foothold on the target system.

Exploitation does not require any privileges, though user interaction (Required) is needed, which slightly reduces the risk of mass automated attacks.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), availability disruption (denial of service), with a CVSS base score of 7.8.

From a weakness classification perspective (CWE-416): Use-after-free vulnerabilities involve accessing memory after it has been freed, often enabling arbitrary code execution.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorLocal
Attack ComplexityLow
Privileges Req.None
User InteractionRequired
ScopeUnchanged
Impact
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Affected Vendors & Products

Fedora1 product(s)
fedora
Red Hat1 product(s)
enterprise linux
ytnef_project1 product(s)
ytnef
Source: NVD CPE · 3 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

ADVISORYhttps://bugzilla.redhat.com/show_bug.cgi?id=1926967
ADVISORYhttps://github.com/Yeraze/ytnef/issues/85
ADVISORYhttps://bugzilla.redhat.com/show_bug.cgi?id=1926967
ADVISORYhttps://github.com/Yeraze/ytnef/issues/85

All References (4)

→
https://bugzilla.redhat.com/show_bug.cgi?id=1926967Issue Tracking · Third Party Advisory
→
https://github.com/Yeraze/ytnef/issues/85Exploit · Issue Tracking · Third Party Advisory
→
https://bugzilla.redhat.com/show_bug.cgi?id=1926967Issue Tracking · Third Party Advisory
→
https://github.com/Yeraze/ytnef/issues/85Exploit · Issue Tracking · Third Party Advisory

Quick Facts

CVE IDCVE-2021-3403
CVSS Score7.8 / 10
SeverityHIGH
WeaknessCWE-416
CISA KEVNo
Affected3 vendor(s)
PublishedMar 4, 2021

Related CVEs (CWE-416)

CVE-2015-3075
10.0
CVE-2015-5586
10.0
CVE-2015-3053
10.0
CVE-2015-3059
10.0
CVE-2024-43102
10.0
CVE-2015-6683
10.0

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-3403 in threat intel feeds
  • →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.
← All Vulnerabilities·Search for CVE-2021-3403·NVD