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CVE-2021-4249

24
FAUCET Score

CVE-2021-4249 is a problematic vulnerability affecting the haskell xml-conduit library, specifically within the DOCTYPE Entity Expansion Handler in xml-conduit/src/Text/XML/Stream/Parse.hs. This flaw allows for an infinite loop due to improper handling of XML entities. With a CVSS score of 7.5 (HIGH), this vulnerability can be exploited remotely without user interaction, leading to a denial of service (availability impact). The attack complexity is low, making it relatively easy to exploit. There is currently no evidence of active exploitation, and no public exploit code is available in Metasploit, Nuclei, or ExploitDB. Community discussion and media coverage for this CVE are minimal.

Impacted Technologies

VendorProductVersion(s)CPE
< 1.9.1.0CPE matchmatch criteria
cpe:2.3:a:haskell:xml-conduit:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

4.3MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
2.8
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.80%
Probability of exploitation in next 30 days
EPSS Percentile
52.7%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0080 is in the 28th percentile among its peer group of 51,466 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 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

Patch Available

Vendor Patches (1)

github_advisorypatch availablevia nvd_reference
View patch

References

github.com / snoyberg/xml/commit/4be1021791dcdee8b164d239433a2043dc0939ea
PatchThird Party Advisory
github.com / snoyberg/xml/pull/161
PatchThird Party Advisory
hackage.haskell.org / package/xml-conduit-1.9.1.0
Release NotesVendor Advisory
vuldb.com
Third Party Advisory