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CVE-2020-25739

Gon gem lack of escaping certain input when outputting as JSON

6.1 MediumFix available

An issue was discovered in the gon gem before gon-6.4.0 for Ruby. MultiJson does not honor the escape_mode parameter to escape fields as an XSS protection mechanism. To mitigate, json_dumper.rb in gon now does escaping for XSS by default without relying on MultiJson.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
Required

What an attacker can affect

Confidentiality
Low
Integrity
Low
Availability
None

Exploit likelihood

1.38%Up 0.5 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 6.1

An issue was discovered in the gon gem before gon-6.4.0 for Ruby. MultiJson does not honor the escape_mode parameter to escape fields as an XSS protection mechanism. To mitigate, json_dumper.rb in gon now does escaping for XSS by default without relying on MultiJson.

Record
CVE-2020-25739
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
CVSS 2.0
4.3 MediumAV:N/AC:M/Au:N/C:N/I:P/A:N
Weakness
CWE-79
Updated
2026-11-02
CVE List No score

An issue was discovered in the gon gem before gon-6.4.0 for Ruby. MultiJson does not honor the escape_mode parameter to escape fields as an XSS protection mechanism. To mitigate, json_dumper.rb in gon now does escaping for XSS by default without relying on MultiJson.

Record
CVE-2020-25739
Updated
2026-11-02
EUVDEUVD-2021-0786 No score

An issue was discovered in the gon gem before gon-6.4.0 for Ruby. MultiJson does not honor the escape_mode parameter to escape fields as an XSS protection mechanism. To mitigate, json_dumper.rb in gon now does escaping for XSS by default without relying on MultiJson.

Record
EUVD-2021-0786
Updated
2026-11-03
GitHub AdvisoriesGHSA-78vq-9j56-wrfr 6.1

Gon gem lack of escaping certain input when outputting as JSON

An issue was discovered in the gon gem before gon-6.4.0 for Ruby. MultiJson does not honor the escape_mode parameter to escape fields as an XSS protection mechanism. To mitigate, json_dumper.rb in gon now does escaping for XSS by default without relying on MultiJson.

Record
GHSA-78vq-9j56-wrfr
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
OSV 6.1

An issue was discovered in the gon gem before gon-6.4.0 for Ruby. MultiJson does not honor the escape_mode parameter to escape fields as an XSS protection mechanism. To mitigate, json_dumper.rb in gon now does escaping for XSS by default without relying on MultiJson.

Record
CVE-2020-25739
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2020-25739 6.1

An issue was discovered in the gon gem before gon-6.4.0 for Ruby. MultiJson does not honor the escape_mode parameter to escape fields as an XSS protection mechanism. To mitigate, json_dumper.rb in gon now does escaping for XSS by default without relying on MultiJson.

Record
DEBIAN-CVE-2020-25739
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVGHSA-78vq-9j56-wrfr 6.1

Gon gem lack of escaping certain input when outputting as JSON

An issue was discovered in the gon gem before gon-6.4.0 for Ruby. MultiJson does not honor the escape_mode parameter to escape fields as an XSS protection mechanism. To mitigate, json_dumper.rb in gon now does escaping for XSS by default without relying on MultiJson.

Record
GHSA-78vq-9j56-wrfr
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Weakness
CWE-79
Updated
2026-11-02
OSVUBUNTU-CVE-2020-25739 6.1

An issue was discovered in the gon gem before gon-6.4.0 for Ruby. MultiJson does not honor the escape_mode parameter to escape fields as an XSS protection mechanism. To mitigate, json_dumper.rb in gon now does escaping for XSS by default without relying on MultiJson.

Record
UBUNTU-CVE-2020-25739
CVSS 3.1
6.1 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
Updated
2026-11-02
OSVUSN-4560-1 No score

ruby-gon vulnerability

It was discovered that Gon gem did not properly escape certain input. An attacker could use this vulnerability to execute a cross-site scripting (XSS) attack.

Record
USN-4560-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
gon
RubyGems
 before 6.4.0
6.4.0
ruby-gon
Debian:12
 before 6.4.0-1
6.4.0-1
ruby-gon
Debian:9
 before 6.1.0-1+deb9u1, plus listed versions
6.1.0-1
6.1.0-1+deb9u1
gon
RubyGems
 before 6.4.0, plus listed versions
0.1.00.1.10.2.00.2.10.2.2
Show 45 moreShow less
0.3.01.0.01.1.01.1.11.1.21.1.32.0.02.0.12.0.22.0.32.0.42.0.52.0.62.1.02.1.22.2.02.2.22.3.03.0.03.0.23.0.33.0.43.0.54.0.04.0.14.0.24.0.34.1.04.1.15.0.05.0.15.0.25.0.35.0.45.1.05.1.15.1.25.2.05.2.15.2.25.2.36.0.06.0.16.1.06.2.0
6.4.0
ruby-gon
Ubuntu:16.04:LTS
 All versions, plus listed versions
5.2.3-26.0.1-1
 None known
ruby-gon
Ubuntu:18.04:LTS
 before 6.1.0-1+deb9u1build0.18.04.1, plus listed versions
6.1.0-1
6.1.0-1+deb9u1build0.18.04.1
ruby-gon
Ubuntu:20.04:LTS
 All versions, plus listed versions
6.2.1-16.3.2-1
 None known

History

History
RecordedChangedSources
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2020-25739 is a medium vulnerability (CVSS 6.1) in Gon Project Gon, published September 23, 2020. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.38%, the 72nd percentile. Fixed in gon 6.4.0.

References

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Left out here: 3 versions. The JSON record has them.

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