How severe is CVE-2017-9785?

CVE-2017-9785 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2017-9785 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2017-9785?

CVE-2017-9785 primarily affects Nancyfx Nancy. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2017-9785?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2017-9785 published?

CVE-2017-9785 was published on 2017-07-20 and last updated on 2026-06-17.

CVE-2017-9785

CVE-2017-9785 is a critical-severity vulnerability in Nancyfx Nancy with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-502.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 3% (86th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-502
Affected product: Nancyfx Nancy
Published: 2017-07-20
Last modified: 2026-06-17

Description

Csrf.cs in NancyFX Nancy before 1.4.4 and 2.x before 2.0-dangermouse has Remote Code Execution via Deserialization of JSON data in a CSRF Cookie.

Frequently asked questions

What is CVE-2017-9785?: Csrf.cs in NancyFX Nancy before 1.4.4 and 2.x before 2.0-dangermouse has Remote Code Execution via Deserialization of JSON data in a CSRF Cookie.
How severe is CVE-2017-9785?: CVE-2017-9785 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2017-9785 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2017-9785?: CVE-2017-9785 primarily affects Nancyfx Nancy. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2017-9785?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2017-9785 published?: CVE-2017-9785 was published on 2017-07-20 and last updated on 2026-06-17.

References

https://github.com/NancyFx/Nancy/releases/tag/v1.4.4

Affected products (4)

cpe:2.3:a:nancyfx:nancy:*:*:*:*:*:*:*:*
cpe:2.3:a:nancyfx:nancy:2.0.0:alpha:*:*:*:*:*:*
cpe:2.3:a:nancyfx:nancy:2.0.0:barneyrubble:*:*:*:*:*:*
cpe:2.3:a:nancyfx:nancy:2.0.0:clinteastwood:*:*:*:*:*:*

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