CVE-2023-29549Network attack vector

JavaScript sandbox weakening via bound-constructor realm confusion

Published Jun 2, 2023 · Updated Jan 10, 2025

Realm confusion in Mozilla Firefox, Firefox for Android, and Firefox Focus for Android before 112 allows attackers to weaken JavaScript sandboxes. During bound constructor calls, SpiderMonkey creates the receiver before switching to the target function's realm, assigning the receiver to the caller's realm. A victim must run attacker-controlled JavaScript inside a JavaScript-implemented sandbox such as SES; the documented consequence is sandbox boundary weakening, not native-code execution.

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

Realm confusion in Mozilla Firefox, Firefox for Android, and Firefox Focus for Android before 112 allows attackers to weaken JavaScript sandboxes. During bound constructor calls, SpiderMonkey creates the receiver before switching to the target function's realm, assigning the receiver to the caller's realm. A victim must run attacker-controlled JavaScript inside a JavaScript-implemented sandbox such as SES; the documented consequence is sandbox boundary weakening, not native-code execution.

The record

CVE
CVE-2023-29549
Published
Jun 2, 2023
Updated
Jan 10, 2025
Vendor
Mozilla
Product
Firefox
Classifications
CWE-326
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 2, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 10, 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 <112

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <112
Mozilla · Firefox for Androidversion=unspecified <112
Mozilla · Firefox Focus for Androidversion=unspecified <112

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-326Inadequate Encryption Strength

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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