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CVE Record

CVE-2026-6747: Use-after-free in the WebRTC component

Use-after-free in the WebRTC component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-6747 is a high-severity memory safety flaw in Mozilla's WebRTC component. Mozilla says it is fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10. The published CVSS data points to service disruption risk, not confirmed data theft or code execution.

Executive priority

Prioritize remediation in normal high-severity patch cycles, especially on managed endpoints and Linux fleets. Business risk is mainly service disruption from a remotely reachable browser/mail component, with no source-backed active exploitation claim.

Technical view

The issue is described as a use-after-free in WebRTC, mapped to CWE-416 and CWE-825. CVSS 3.1 is 7.5 with network attack vector, low complexity, no privileges, no user interaction, unchanged scope, and availability-only impact. Public sources do not provide exploit mechanics.

Likely exposure

Organizations using Firefox, Firefox ESR, or Thunderbird before the fixed Mozilla releases may be exposed. Linux environments should also check distributor packages, including Red Hat errata referenced for this CVE.

Exploitation context

The source bundle marks CISA KEV as false and provides no cited evidence of active exploitation. Treat this as patch-priority high due to remote, low-complexity availability impact, but do not claim exploitation without additional evidence.

Researcher notes

Public detail is limited to component, weakness class, fixed releases, CVSS vector, and vendor advisories. Avoid inferring exploitability beyond availability impact. Bugzilla and distributor advisories are useful for package tracking, but the supplied sources do not include weaponizable technical detail.

Mitigation direction

  • Update Firefox to 150 or later where applicable.
  • Update Firefox ESR to 140.10 or later.
  • Update Thunderbird to 150 or 140.10 or later as applicable.
  • Apply relevant Red Hat security errata for packaged Mozilla components.
  • Monitor Mozilla and distributor advisories for corrected package availability.

Validation and detection

  • Inventory Firefox, Firefox ESR, and Thunderbird versions across endpoints and servers.
  • Compare installed versions against Mozilla fixed releases listed for this CVE.
  • Check Red Hat package status against the referenced RHSA advisories.
  • Confirm endpoint management reports successful browser and mail-client updates.
  • Review vulnerability scanner findings for stale Mozilla package detections.
Prepared
Confidence
medium
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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 · low confidence lookup

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 lookup
cwe · low confidence lookup

CWE-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 lookup
cve · low confidence lookup

CVE-2026-6747 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Official CVE source material

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.

2CVSS vectors
5Timeline events
2ADP providers
36Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We 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.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6CISA-ADP
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H1.65.9redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-6747Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
redhat-SADPfirefox: thunderbird: Use-after-free in the WebRTC component
other:Red Hat severity ratingcvssV3_1
  • 2026-04-21T14:02:14.211Z: Reported to Red Hat.
  • 2026-04-21T12:40:45.203Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
MozillaFirefox140.10, 150Listed
MozillaThunderbird140.10, 150Listed
Weakness

CWE details

CWE-416CWE-825

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-416 · source CWE mapping

Use After Free

Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-825 · source CWE mapping

Expired Pointer Dereference

Expired Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs