CVE-2025-1013Public exploitNetwork attack vector

Private-tab exposure via browsing-window teardown race

Published Feb 4, 2025 · Updated Apr 13, 2026

Race condition in Mozilla Firefox and Thunderbird before 135 or ESR 128.7 allows attackers to expose private tabs in normal windows. During private-browsing teardown, ContentParent falls back to a normal window for a pending window.open request even when privateBrowsingId remains set. Triggering it requires a popup-allowlisted page to keep opening tabs while the user closes the private window; cookies stay private, but tabs and authenticated content appear in a normal window.

CVSS severity6.5
Medium
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Race condition in Mozilla Firefox and Thunderbird before 135 or ESR 128.7 allows attackers to expose private tabs in normal windows. During private-browsing teardown, ContentParent falls back to a normal window for a pending window.open request even when privateBrowsingId remains set. Triggering it requires a popup-allowlisted page to keep opening tabs while the user closes the private window; cookies stay private, but tabs and authenticated content appear in a normal window.

The record

CVE
CVE-2025-1013
Published
Feb 4, 2025
Updated
Apr 13, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-362
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 4, 2025CVE publishedPublication date reported by the CVE source.
  2. Apr 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/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 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-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

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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