CVE-2020-12392Public exploit

Local file disclosure via cURL data-file expansion

Published May 26, 2020 · Updated Aug 4, 2024

Information disclosure in Mozilla Firefox before 76, Firefox ESR before 68.8, and Thunderbird before 68.8.0 allows attackers to read local files. The DevTools Network Monitor emits website-controlled POST bodies with curl's --data option; a body beginning with @ makes curl read the remaining text as a local filename and transmit that file. Exploitation requires a user to copy the crafted request as cURL and execute the generated command in a terminal, limiting disclosure to files readable by that local user.

CVSS severity5.5
Medium
EPSS probability0.35%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Mozilla Firefox before 76, Firefox ESR before 68.8, and Thunderbird before 68.8.0 allows attackers to read local files. The DevTools Network Monitor emits website-controlled POST bodies with curl's --data option; a body beginning with @ makes curl read the remaining text as a local filename and transmit that file. Exploitation requires a user to copy the crafted request as cURL and execute the generated command in a terminal, limiting disclosure to files readable by that local user.

The record

CVE
CVE-2020-12392
Published
May 26, 2020
Updated
Aug 4, 2024
Vendor
Mozilla
Product
Firefox
Classifications
T1204.004
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

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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

5.5CanonicalCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1204.004Malicious Copy and Paste

Public exploit references

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

Technologies

Your stack

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Your stack

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