CVE-2020-1340Network attack vector

Cross-site scripting via unsafe package metadata rendering

Published Jun 9, 2020 · Updated Aug 4, 2024

Cross-site scripting in Microsoft NuGet Gallery before 2020.06.09 allows remote authenticated users to spoof rendered package metadata. PreFormattedText matched URLs after encoding the full metadata value and inserted matched link values into raw anchor markup instead of encoding each output context. Exploitation requires package-publishing access and viewer interaction, and crafted metadata can misrepresent link content or affect browser-accessible data.

CVSS severity5.4
Medium
EPSS probability1.58%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cross-site scripting in Microsoft NuGet Gallery before 2020.06.09 allows remote authenticated users to spoof rendered package metadata. PreFormattedText matched URLs after encoding the full metadata value and inserted matched link values into raw anchor markup instead of encoding each output context. Exploitation requires package-publishing access and viewer interaction, and crafted metadata can misrepresent link content or affect browser-accessible data.

The record

CVE
CVE-2020-1340
Published
Jun 9, 2020
Updated
Aug 4, 2024
Vendor
Microsoft
Product
NuGet Gallery
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 9, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Microsoft · NuGet Galleryversion=unspecified

Published CVSS scores

3.5NIST National Vulnerability DatabaseAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4NIST National Vulnerability DatabaseCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo