CVE-2020-12393Public exploit

Command execution via unescaped HTTP method

Published May 26, 2020 · Updated Aug 4, 2024

Command injection in Firefox before 76, Firefox ESR before 68.8, and Thunderbird before 68.8.0 allows attackers to execute Windows commands. DevTools Network Monitor inserts a website-controlled HTTP method into Copy as cURL output without escaping PowerShell subexpression syntax. Exploitation requires a user to copy the crafted request as cURL and paste it into PowerShell, where commands run with that user's privileges.

CVSS severity7.8
High
EPSS probability1.01%
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

Command injection in Firefox before 76, Firefox ESR before 68.8, and Thunderbird before 68.8.0 allows attackers to execute Windows commands. DevTools Network Monitor inserts a website-controlled HTTP method into Copy as cURL output without escaping PowerShell subexpression syntax. Exploitation requires a user to copy the crafted request as cURL and paste it into PowerShell, where commands run with that user's privileges.

The record

CVE
CVE-2020-12393
Published
May 26, 2020
Updated
Aug 4, 2024
Vendor
Mozilla
Product
Firefox
Classifications
CWE-78, T1204.004, T1059.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 26, 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 <76

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <76
Mozilla · Thunderbirdversion=unspecified <68.8.0
Mozilla · Firefox ESRversion=unspecified <68.8

Published CVSS scores

4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P
7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1204.004User Execution: Malicious Copy and Paste
T1059.001Command and Scripting Interpreter: PowerShell

Public exploit references

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