Mozilla Firefox/Firefox ESR/Thunderbird HTML Input Element use after free

CVSS Meta Temp Score
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CTI Interest Score
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6.0$5k-$25k0.00

Summaryinfo

A vulnerability marked as critical has been reported in Mozilla Firefox, Firefox ESR and Thunderbird. This affects an unknown part of the component HTML Input Element Handler. This manipulation causes use after free. The identification of this vulnerability is CVE-2021-38504. It is possible to initiate the attack remotely. There is no exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical was found in Mozilla Firefox, Firefox ESR and Thunderbird (Web Browser) (the affected version is unknown). Affected by this vulnerability is an unknown code of the component HTML Input Element Handler. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability.

The weakness was shared 12/09/2021. The advisory is shared at mozilla.org. This vulnerability is known as CVE-2021-38504 since 08/10/2021. It demands that the victim is doing some kind of user interaction. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/11/2025).

The vulnerability scanner Nessus provides a plugin with the ID 247394 (Linux Distros Unpatched Vulnerability : CVE-2021-38504), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (247394). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

Vendor

Name

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.3
VulDB Meta Temp Score: 6.0

VulDB Base Score: 6.3
VulDB Temp Score: 6.0
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Yes

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 247394
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2021-38504

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Timelineinfo

08/10/2021 🔍
12/09/2021 +121 days 🔍
12/09/2021 +0 days 🔍
08/11/2025 +1340 days 🔍

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: mozilla.org
Status: Confirmed

CVE: CVE-2021-38504 (🔍)
GCVE (CVE): GCVE-0-2021-38504
GCVE (VulDB): GCVE-100-187849

Entryinfo

Created: 12/09/2021 08:35
Updated: 08/11/2025 00:07
Changes: 12/09/2021 08:35 (38), 12/11/2021 22:31 (1), 12/11/2021 22:44 (1), 08/11/2025 00:07 (16)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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