CVE-2026-4705Network attack vector

Unspecified impact via WebRTC signaling undefined behavior

Published Mar 24, 2026 · Updated Mar 24, 2026

Undefined behavior in Mozilla Firefox, Firefox ESR, and Thunderbird allows remote attackers to cause unspecified impact via WebRTC signaling. The referenced WebRTC: Signaling bug is access-restricted, and Mozilla has not published the concrete code locus or the operation that invokes undefined behavior. The published assessment describes unauthenticated network reachability without user interaction, but it does not identify the triggering input or any required configuration.

CVSS severity9.8
Critical
EPSS probability0.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Undefined behavior in Mozilla Firefox, Firefox ESR, and Thunderbird allows remote attackers to cause unspecified impact via WebRTC signaling. The referenced WebRTC: Signaling bug is access-restricted, and Mozilla has not published the concrete code locus or the operation that invokes undefined behavior. The published assessment describes unauthenticated network reachability without user interaction, but it does not identify the triggering input or any required configuration.

The record

CVE
CVE-2026-4705
Published
Mar 24, 2026
Updated
Mar 24, 2026
Vendor
Mozilla
Product
Firefox
Classifications
CWE-758
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 24, 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?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=unspecified <149

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Mozilla · Firefoxversion=unspecified <149
Mozilla · Thunderbirdversion=unspecified <140.9; version=unspecified <149
Mozilla · Firefox ESRversion=unspecified <140.9

Published CVSS scores

9.8CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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 exploitUnconfirmed

Weakness, pattern, technique

CWE-758Reliance on Undefined, Unspecified, or Implementation-Defined Behavior

Public exploit references

No public exploit references are available in this record.

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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