Security readout for executives and security teams
Plain-English summary
CVE-2026-8390 is a high-severity memory safety flaw in Firefox's JavaScript WebAssembly component. A successful attack could affect confidentiality, integrity, and availability, but the CVSS vector requires user interaction and high attack complexity. Mozilla states it was fixed in Firefox 150.0.3.
Executive priority
Treat this as a prompt browser patching item, not an emergency exploitation incident based on the supplied evidence. Focus on managed Firefox update completion and exception tracking.
Technical view
The issue is a use-after-free weakness, mapped to CWE-416 and CWE-825, in Firefox's JavaScript WebAssembly component. The provided CVSS 3.1 score is 7.5 with network attack vector, no privileges required, user interaction required, high complexity, and high impact across confidentiality, integrity, and availability.
Likely exposure
Primary exposure is Mozilla Firefox deployments that have not received the 150.0.3 fix. The bundle does not provide an exact affected version range below 150.0.3 or confirm impact for Firefox-derived products.
Exploitation context
The provided data does not show CISA KEV listing or any cited source confirming active exploitation. Exploitation should not be assumed, but browser memory safety flaws exposed to web content warrant prompt patch management.
Researcher notes
Evidence is limited to the CVE record, Mozilla advisory reference, Bugzilla links, and Red Hat tracking. Do not infer active exploitation, affected forks, or precise vulnerable version ranges without vendor confirmation.
Mitigation direction
- Update Firefox to version 150.0.3 or a vendor-provided fixed build.
- Check Mozilla MFSA2026-45 for official remediation details.
- Check Red Hat guidance for package-specific status in managed Linux environments.
- Prioritize updates for users who browse untrusted or high-risk web content.
Validation and detection
- Inventory Firefox versions across managed endpoints.
- Confirm installed builds are Firefox 150.0.3 or vendor-fixed equivalents.
- Review vulnerability scanner findings against CVE-2026-8390.
- Track Mozilla and Red Hat advisories for status changes.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-416: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-825: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-8390 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H1.65.9redhat-SADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L3.93.4CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
7.5HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H
Base CVSS 3.1 score
7.3HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- ADP timelineredhat-SADP
Made public.
- CVE publishedCVE Program
The CVE record was published.
- ADP timelineredhat-SADP
Reported to Red Hat.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-05-12T14:01:48.857Z: Reported to Red Hat.
- 2026-05-12T12:36:13.948Z: Made public.
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.mozilla.org/show_bug.cgi?id=2038081CVE reference, mozilla
- https://www.mozilla.org/security/advisories/mfsa2026-45/CVE reference, mozilla
- https://access.redhat.com/security/cve/CVE-2026-8390CVE reference, redhat-SADP · vdb-entry, x_refsource_REDHAT
- RHBZ#2476474CVE reference, redhat-SADP · issue-tracking, x_refsource_REDHAT
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-8390.jsonCVE reference, redhat-SADP · x_sadp-csaf-vex
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Expired Pointer Dereference
Expired Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.