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CVE-2021-27671

19
FAUCET Score

CVE-2021-27671 describes a cross-site scripting (XSS) vulnerability in the comrak Rust crate prior to version 0.9.1. This flaw arises because the URI protection mechanism is case-sensitive, allowing attackers to bypass safeguards by using variations like "Data:" instead of "data:" in URIs. Rated 6.1 MEDIUM, this vulnerability has a network attack vector, low complexity, and requires user interaction, potentially leading to limited impact on confidentiality and integrity. There is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.9.1CPE matchmatch criteria
cpe:2.3:a:comrak_project:comrak:*:*:*:*:*:rust:*:*

CVSS Data

CVSS version used by this source: 3.1

6.1MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
CHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
2.8
Impact Score
2.7
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.69%
Probability of exploitation in next 30 days
EPSS Percentile
48.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0069 is in the 54th percentile among its peer group of 26,234 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

Patch Available

Vendor Patches (1)

rustpatch availablevia ghsa
Product: comrakFixed in: 0.9.1

Vendor Advisories (1)

rustGHSA-xmr7-v725-2jjrmedium

Cross site scripting in comrak

Aug 25, 2021

References

rustsec.org / advisories/RUSTSEC-2021-0026.html
Third Party Advisory