CVE-2022-31739Public exploitNetwork attack vector

File placement via unescaped environment variables

Published Dec 22, 2022 · Updated Apr 16, 2025

Path traversal in Mozilla Firefox before 101 and Firefox ESR and Thunderbird before 91.10 allows remote attackers to redirect downloads. The Windows system file picker accepts a suggested download name without replacing percent signs, so strings such as %HOMEPATH% or %APPDATA% expand into attacker-influenced destinations. Exploitation requires a user-triggered download; placement in the user's Startup folder causes the saved file to execute at a later sign-in.

CVSS severity8.8
High
EPSS probability0.66%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Mozilla Firefox before 101 and Firefox ESR and Thunderbird before 91.10 allows remote attackers to redirect downloads. The Windows system file picker accepts a suggested download name without replacing percent signs, so strings such as %HOMEPATH% or %APPDATA% expand into attacker-influenced destinations. Exploitation requires a user-triggered download; placement in the user's Startup folder causes the saved file to execute at a later sign-in.

The record

CVE
CVE-2022-31739
Published
Dec 22, 2022
Updated
Apr 16, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-73, T1060
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 22, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 16, 2025Record 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 <101

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <101
Mozilla · Thunderbirdversion=unspecified <91.10
Mozilla · Firefox ESRversion=unspecified <91.10

Published CVSS scores

8.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
8.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/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)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-73External Control of File Name or Path
T1060Registry Run Keys / Startup Folder

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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