HOMEVULNERABILITIESCVE-2021-4249
HIGH

CVE-2021-4249

CWE-404Published: December 18, 2022· Updated: Jun 17, 2026

7.5
CVSS v3.1

Official Description

A vulnerability was found in xml-conduit. It has been classified as problematic. Affected is an unknown function of the file xml-conduit/src/Text/XML/Stream/Parse.hs of the component DOCTYPE Entity Expansion Handler. The manipulation leads to infinite loop. It is possible to launch the attack remotely. Upgrading to version 1.9.1.0 is able to address this issue. The name of the patch is 4be1021791dcdee8b164d239433a2043dc0939ea. It is recommended to upgrade the affected component. The identifier of this vulnerability is VDB-216204.

NVD Source

Technical Analysis

CVE-2021-4249 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected Vendors & Products

haskell1 product(s)
xml-conduit
Source: NVD CPE · 1 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

PATCHhttps://github.com/snoyberg/xml/commit/4be1021791dcdee8b164d239433a2043dc0939ea
PATCHhttps://github.com/snoyberg/xml/pull/161
PATCHhttps://github.com/snoyberg/xml/commit/4be1021791dcdee8b164d239433a2043dc0939ea
PATCHhttps://github.com/snoyberg/xml/pull/161
ADVISORYhttps://hackage.haskell.org/package/xml-conduit-1.9.1.0
ADVISORYhttps://vuldb.com/?id.216204
ADVISORYhttps://hackage.haskell.org/package/xml-conduit-1.9.1.0
ADVISORYhttps://vuldb.com/?id.216204

All References (8)

→
https://github.com/snoyberg/xml/commit/4be1021791dcdee8b164d239433a2043dc0939eaPatch · Third Party Advisory
→
https://github.com/snoyberg/xml/pull/161Patch · Third Party Advisory
→
https://hackage.haskell.org/package/xml-conduit-1.9.1.0Release Notes · Vendor Advisory
→
https://vuldb.com/?id.216204Third Party Advisory
→
https://github.com/snoyberg/xml/commit/4be1021791dcdee8b164d239433a2043dc0939eaPatch · Third Party Advisory
→
https://github.com/snoyberg/xml/pull/161Patch · Third Party Advisory
→
https://hackage.haskell.org/package/xml-conduit-1.9.1.0Release Notes · Vendor Advisory
→
https://vuldb.com/?id.216204Third Party Advisory

Quick Facts

CVE IDCVE-2021-4249
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-404
CISA KEVNo
Affected1 vendor(s)
PublishedDec 18, 2022

Related CVEs (CWE-404)

CVE-2025-5867
9.8
CVE-2023-24444
9.8
CVE-2018-8450
8.8
CVE-2026-1875
8.7
CVE-2026-1876
8.7
CVE-2026-11317
8.7

Recommended Actions

  • →Apply vendor patches immediately
  • →Monitor CVE-2021-4249 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.COM. CVE data is provided under the NVD usage policy.
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