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CVE-2017-9785

30
FAUCET Score

CVE-2017-9785 is a critical remote code execution vulnerability affecting NancyFX Nancy versions prior to 1.4.4 and 2.x before 2.0-dangermouse. It stems from insecure deserialization of JSON data within a CSRF cookie, allowing unauthenticated attackers to execute arbitrary code. With a CVSS score of 9.8, this vulnerability is easily exploitable over the network with no user interaction, leading to complete compromise of confidentiality, integrity, and availability. While not listed in CISA KEV and lacking public exploit code, its high FAUCET Risk Score and mention in media coverage highlight its significant potential impact.

Impacted Technologies

VendorProductVersion(s)CPE
<= 1.4.3CPE matchmatch criteria
cpe:2.3:a:nancyfx:nancy:*:*:*:*:*:*:*:*
2.0.0CPE matchmatch criteria
cpe:2.3:a:nancyfx:nancy:2.0.0:alpha:*:*:*:*:*:*
2.0.0CPE matchmatch criteria
cpe:2.3:a:nancyfx:nancy:2.0.0:barneyrubble:*:*:*:*:*:*
2.0.0CPE matchmatch criteria
cpe:2.3:a:nancyfx:nancy:2.0.0:clinteastwood:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

9.8CRITICAL

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.0

Exploit Intelligence

EPSS Score
3.09%
Probability of exploitation in next 30 days
EPSS Percentile
86.3%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
This CVE's current EPSS score of 0.0309 is in the 78th percentile among its peer group of 36,829 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

nugetpatch availablevia ghsa
Product: NancyFixed in: 1.4.4
nugetpatch availablevia ghsa
Product: NancyFixed in: 2.0.0

Vendor Advisories (1)

nugetGHSA-mx3q-j2g2-5qxqcritical

Deserialization of Untrusted Data in NancyFX Nancy

May 17, 2022

References

github.com / NancyFx/Nancy/releases/tag/v1.4.4
Release NotesThird Party Advisory