Mozilla Firefox up to 115.44/153.6/159 HTML Parser use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
6.0$5k-$25k0.00+

Summaryinfo

A vulnerability, which was classified as critical, has been found in Mozilla Firefox up to 115.44/153.6/159. Affected by this issue is some unknown functionality of the component HTML Parser. Performing a manipulation results in use after free. This vulnerability is known as CVE-2026-124863. Remote exploitation of the attack is possible. No exploit is available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Mozilla Firefox up to 115.44/153.6/159. This affects an unknown functionality of the component HTML Parser. The manipulation with an unknown input leads to a use after free vulnerability. CWE is classifying the issue as CWE-416. The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

Use-after-free in the DOM: HTML Parser component. This vulnerability was fixed in Firefox 160, Firefox ESR 115.45, and Firefox ESR 153.7.

The advisory is shared at bugzilla.mozilla.org. This vulnerability is uniquely identified as CVE-2026-124863 since 11/09/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. 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 11/10/2026).

Upgrading to version 115.45, 153.7 or 160 eliminates this vulnerability.

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

Productinfo

Type

Vendor

Name

Version

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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💳💳💳💳💳💳
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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
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Firefox 115.45/153.7/160

Timelineinfo

11/09/2026 CVE reserved
11/10/2026 +1 days Advisory disclosed
11/10/2026 +0 days VulDB entry created
11/10/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CNA: mozilla
CVE: CVE-2026-124863 (🔒)

GCVE (CVE): GCVE-0-2026-124863
GCVE (VulDB): GCVE-100-433665

Entryinfo

Created: 11/10/2026 14:54
Changes: 11/10/2026 14:54 (57)
Complete: 🔍
Cache ID: 216::103

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

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