CVE-2026-5734 | Mozilla Firefox up to 149.0.1 memory corruption

VDB-355740 · CVE-2026-5734 · GCVE-0-2026-5734 MOZILLA FIREFOX UP TO 149.0.1 MEMORY CORRUPTION HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 6.0 $5k-$25k 1.55+ 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 affects Firefox < 149.0.2 and Firefox ESR < 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 04/07/2026). Upgrading to version 149.0.2 eliminates this vulnerability. Productinfo Type Web Browser Vendor Mozilla Name Firefox Version 149.0.0 149.0.1 License open-source Website Vendor: https://www.mozilla.org/ Product: https://www.mozilla.org/en-US/firefox/ 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 Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock 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 Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock 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 04/07/2026 +0 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 Entryinfo Created: 04/07/2026 15:28 Changes: 04/07/2026 15:28 (55) Complete: 🔍 Cache ID: 99:1DC:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸