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CVE-2021-23824

21
FAUCET Score

CVE-2021-23824 describes a Cross-site Scripting (XSS) vulnerability in the Crow C++ web framework, specifically affecting versions prior to 0.3+4. This flaw arises when templates use unquoted attributes, allowing an attacker to inject additional attributes and potentially execute arbitrary code if they can control template input. The vulnerability carries a CVSS score of 6.1 (Medium), indicating it can be exploited remotely with low complexity, requiring user interaction, and potentially leading to low confidentiality and integrity impacts. Currently, there is no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
< 0.3\+4CPE matchmatch criteria
cpe:2.3:a:crowcpp:crow:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

6.5MEDIUM

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
LOW
Integrity Impact
LOW
Availability Impact
NONE
Exploitability Score
3.9
Impact Score
2.5
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.92%
Probability of exploitation in next 30 days
EPSS Percentile
56.6%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.0092 is in the 68th percentile among its peer group of 26,221 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)

github_advisorypatch availablevia nvd_reference
View patch

References

github.com / CrowCpp/Crow/pull/317
Issue TrackingPatchThird Party Advisory
github.com / CrowCpp/Crow/releases/tag/v0.3%2B4
Release NotesThird Party Advisory
snyk.io / vuln/SNYK-UNMANAGED-CROW-2336164
ExploitThird Party Advisory