CVE-2022-26386

Local file disclosure via shared temporary directory

Published Dec 22, 2022 · Updated Apr 15, 2025

Insecure temporary-file handling in Mozilla Firefox ESR and Thunderbird before 91.7 allows local users to access downloaded files. On Linux and macOS, the download handler places temporary downloads directly in shared /tmp instead of a user-owned, mode-0700 subdirectory, leaving filenames observable and file contents accessible to another account. Exploitation requires another local account and a victim-triggered temporary download; Windows is unaffected, and the bounded consequence is disclosure of those files.

CVSS severity6.5
Medium
EPSS probability0.68%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure temporary-file handling in Mozilla Firefox ESR and Thunderbird before 91.7 allows local users to access downloaded files. On Linux and macOS, the download handler places temporary downloads directly in shared /tmp instead of a user-owned, mode-0700 subdirectory, leaving filenames observable and file contents accessible to another account. Exploitation requires another local account and a victim-triggered temporary download; Windows is unaffected, and the bounded consequence is disclosure of those files.

The record

CVE
CVE-2022-26386
Published
Dec 22, 2022
Updated
Apr 15, 2025
Vendor
Mozilla
Product
Thunderbird
Classifications
CWE-377, T1005
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 22, 2022CVE publishedPublication date reported by the CVE source.
  2. Apr 15, 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 <91.7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Mozilla · Thunderbirdversion=unspecified <91.7
Mozilla · Firefox ESRversion=unspecified <91.7

Published CVSS scores

6.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N
6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/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.

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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 exploitUnconfirmed

Weakness, pattern, technique

CWE-377Insecure Temporary File
T1005Data from Local System

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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