Mozilla Firefox/Firefox ESR/Thunderbird SMIL Animation Controller use after free

CVSS Meta Temp Score
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CTI Interest Score
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7.9$0-$5k0.00

Summaryinfo

A vulnerability classified as critical has been found in Mozilla Firefox, Firefox ESR and Thunderbird. Impacted is an unknown function of the component SMIL Animation Controller. This manipulation causes use after free. This vulnerability is handled as CVE-2019-9796. The attack can be initiated remotely. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Mozilla Firefox, Firefox ESR and Thunderbird (Web Browser) (version now known). It has been declared as critical. Affected by this vulnerability is some unknown processing of the component SMIL Animation Controller. 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 summary by CVE is:

A use-after-free vulnerability can occur when the SMIL animation controller incorrectly registers with the refresh driver twice when only a single registration is expected. When a registration is later freed with the removal of the animation controller element, the refresh driver incorrectly leaves a dangling pointer to the driver's observer array. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

The bug was discovered 03/19/2019. The weakness was released 04/26/2019 by Markus Vervier (Nils) with X41 D-Sec GmbH (Website). The advisory is shared at access.redhat.com. This vulnerability is known as CVE-2019-9796 since 03/14/2019. The attack can be launched remotely. The exploitation doesn't need any form of authentication. 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 $0-$5k at the moment (estimation calculated on 11/26/2025).

The vulnerability was handled as a non-public zero-day exploit for at least 38 days. During that time the estimated underground price was around $5k-$25k. The vulnerability scanner Nessus provides a plugin with the ID 248454 (Linux Distros Unpatched Vulnerability : CVE-2019-9796), which helps to determine the existence of the flaw in a target environment. The commercial vulnerability scanner Qualys is able to test this issue with plugin 157940 (Oracle Enterprise Linux Security Update for firefox (ELSA-2019-0623)).

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (248454) and SecurityFocus (BID 106773†). Entries connected to this vulnerability are available at VDB-130538, VDB-134153, VDB-134155 and VDB-134156. Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.0
VulDB Meta Temp Score: 7.9

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

NVD Base Score: 9.8
NVD Vector: 🔍

CVSSv2info

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

NVD Base Score: 🔍

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: 248454
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2019-9796

Qualys ID: 🔍
Qualys Name: 🔍

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Timelineinfo

01/29/2019 🔍
03/14/2019 +44 days 🔍
03/19/2019 +5 days 🔍
04/26/2019 +38 days 🔍
04/27/2019 +1 days 🔍
11/26/2025 +2405 days 🔍

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: RHSA-2019:0966
Researcher: Markus Vervier (Nils)
Organization: X41 D-Sec GmbH
Status: Confirmed

CVE: CVE-2019-9796 (🔍)
GCVE (CVE): GCVE-0-2019-9796
GCVE (VulDB): GCVE-100-134161
SecurityFocus: 106773 - Mozilla Firefox MFSA2019-01 Multiple Security Vulnerabilities

See also: 🔍

Entryinfo

Created: 04/27/2019 09:05
Updated: 11/26/2025 09:54
Changes: 04/27/2019 09:05 (61), 06/03/2020 06:55 (7), 09/07/2023 17:46 (4), 08/12/2025 05:00 (16), 11/26/2025 09:54 (1)
Complete: 🔍
Cache ID: 216::103

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

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