VulnerabilityPublished 1 Apr 2025Updated 3 Nov 2025

CVE-2025-3029: A crafted URL containing specific Unicode characters could have hidden the true origin of the page

Source GCVE Database

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Authoritative record:CVE-2025-3029· High 7.3

Not known to be exploited · CVSS 7.3 High · fixed in 137 : patch affected systems soon.

Data as of 30 Oct 2026, 01:23 UTC

CVSS 3.1 base score

7.3High

How severe the flaw is on the 0–10 CVSS scale.

Patch: Available – fixed in 137, 128.9

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: Low
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 1 Apr 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-799g-3g44-3g9m

What to do

AI-suggested

This vulnerability has been fixed in Firefox 137, Firefox ESR 128.9, Thunderbird 137, and Thunderbird ESR 128.9. Users and administrators should update to these versions or later to mitigate the risk. No additional mitigation steps are required beyond applying the official updates.

Description

CVE-2025-3029 is a vulnerability in Firefox and Thunderbird browsers where a crafted URL containing specific Unicode characters can obscure the true origin of the page, potentially enabling a spoofing attack. This flaw affects Firefox versions prior to 137 and Firefox ESR versions prior to 128.9, as well as Thunderbird versions prior to 137 and Thunderbird ESR versions prior to 128.9. The vulnerability was addressed in Firefox 137 and Firefox ESR 128.9 releases.

Impact

The vulnerability allows an attacker to potentially spoof the URL bar by hiding the true origin of a webpage using crafted Unicode characters. This can mislead users into trusting malicious sites, increasing the risk of phishing or other social engineering attacks. The CVSS score is 7.3 (high), indicating significant confidentiality, integrity, and availability impacts, although no active exploitation is currently known.

Summary

This vulnerability involves URL bar spoofing via non-BMP Unicode characters that can hide the true origin of a webpage. An attacker could craft a URL with specific Unicode characters to mislead users about the actual source of the page they are visiting, which may facilitate spoofing attacks. The issue affects Firefox versions before 137, Firefox ESR before 128.9, Thunderbird before 137, and Thunderbird ESR before 128.9. Mozilla fixed this vulnerability in Firefox 137 and Firefox ESR 128.9 as part of their April 1, 2025 security advisories.

CWE-290Authentication Bypass by Spoofing (opens in a new tab)
Base weaknessOWASP Top 10 A07:2025: Authentication Failures (opens in a new tab)
This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks.
OWASP Cheat Sheets
REST Security (opens in a new tab)
JSON Web Token for Java (opens in a new tab)
OWASP Authentication (opens in a new tab)
OWASP ASVS 4.0.3
V3.5.1 (opens in a new tab)
V2.8.5 (opens in a new tab)
V2.8.4 (opens in a new tab)
Attack patterns
Creating a Rogue Certification Authority Certificate (opens in a new tab)
Web Services API Signature Forgery Leveraging Hash Function Extension Weakness (opens in a new tab)
Signature Spoof (opens in a new tab)
Signature Spoofing by Misrepresentation (opens in a new tab)
Session Credential Falsification through Prediction (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 30 Oct 2026, 01:23 UTC

WeaknessesCWE-290

Technical details

References

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