Mozilla Firefox up to 149.0.1 memory corruption

CVSS Meta Temp Score
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CTI Interest Score
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8.0$5k-$25k0.00

Summaryinfo

A vulnerability classified as critical was found in Mozilla Firefox up to 149.0.1. Affected by this vulnerability is an unknown functionality. The manipulation results in memory corruption. This vulnerability is known as CVE-2026-5734. It is possible to launch the attack remotely. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Mozilla Firefox up to 149.0.1. It has been classified as critical. Affected is an unknown function. The manipulation with an unknown input leads to a memory corruption vulnerability. CWE is classifying the issue as CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

Memory safety bugs present in Firefox ESR 140.9.0, Thunderbird ESR 140.9.0, Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149.0.2, Firefox ESR 140.9.1, Thunderbird 149.0.2, and Thunderbird 140.9.1.

The advisory is shared for download at bugzilla.mozilla.org. This vulnerability is traded as CVE-2026-5734 since 04/07/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. Successful exploitation requires user interaction by the victim. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $5k-$25k (estimation calculated on 07/02/2026).

The vulnerability scanner Nessus provides a plugin with the ID 306064 (RHEL 9 : firefox (RHSA-2026:7671)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 149.0.2 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (306064) and CERT Bund (WID-SEC-2026-0997). Once again VulDB remains the best source for vulnerability data.

Affected

  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • SUSE Linux
  • Oracle Linux
  • IGEL OS
  • SUSE openSUSE
  • RESF Rocky Linux
  • Mozilla Firefox
  • Mozilla Firefox ESR
  • Mozilla Thunderbird

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 8.1
VulDB Meta Temp Score: 8.0

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

NVD Base Score: 9.8
NVD Vector: 🔒

ADP CISA Base Score: 8.1
ADP CISA Vector: 🔒

CVSSv2info

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

Exploitinginfo

Class: Memory corruption
CWE: 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: 306064
Nessus Name: RHEL 9 : firefox (RHSA-2026:7671)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Firefox 149.0.2

Timelineinfo

04/07/2026 Advisory disclosed
04/07/2026 +0 days CVE reserved
04/07/2026 +0 days VulDB entry created
07/02/2026 +86 days VulDB entry last update

Sourcesinfo

Vendor: mozilla.org
Product: mozilla.org

Advisory: bugzilla.mozilla.org
Status: Confirmed

CVE: CVE-2026-5734 (🔒)
GCVE (CVE): GCVE-0-2026-5734
GCVE (VulDB): GCVE-100-355740
CERT Bund: WID-SEC-2026-0997 - Mozilla Firefox und Thunderbird: Mehrere Schwachstellen

Entryinfo

Created: 04/07/2026 15:28
Updated: 07/02/2026 04:06
Changes: 04/07/2026 15:28 (55), 04/13/2026 16:13 (2), 04/14/2026 17:11 (7), 04/18/2026 20:53 (1), 04/29/2026 05:10 (1), 05/02/2026 03:06 (1), 07/02/2026 04:06 (21)
Complete: 🔍
Cache ID: 216::103

Once again VulDB remains the best source for vulnerability data.

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