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CVE Record

CVE-2026-6749: Information disclosure due to uninitialized memory in the Graphics: Canvas2D component

Information disclosure due to uninitialized memory in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 150, Firefox ESR 115.35, 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-2026-6749 is a high-severity Mozilla flaw where Firefox or Thunderbird could disclose memory contents because Canvas2D graphics memory was not properly initialized. The main business risk is unintended exposure of sensitive data from browser or mail-client memory. Mozilla lists fixed releases; organizations should prioritize updating managed endpoints.

Executive priority

Patch on a normal high-priority browser and mail-client cycle, accelerated for sensitive users and managed fleets. The issue affects confidentiality, not integrity or availability, and the bundle does not substantiate active exploitation.

Technical view

The issue is an information disclosure vulnerability in Mozilla’s Graphics: Canvas2D component, mapped to CWE-824 and CWE-908. CVSS 3.1 is 7.5, with network attack vector, low complexity, no privileges, no user interaction, unchanged scope, and high confidentiality impact only.

Likely exposure

Exposure is most likely on endpoints running Mozilla Firefox, Firefox ESR, or Thunderbird that have not been updated to the fixed releases named by Mozilla or vendor package maintainers such as Red Hat.

Exploitation context

The provided bundle does not show CISA KEV listing or any cited evidence of active exploitation. Treat this as a remotely reachable confidentiality issue, but do not assume exploitation in the wild from these sources alone.

Researcher notes

Focus validation on version exposure and vendor package status. The source bundle identifies Canvas2D uninitialized memory disclosure but does not provide complete exploit mechanics. Avoid inferring affected downstream products beyond Mozilla and Red Hat references provided.

Mitigation direction

  • Update Firefox to Mozilla’s fixed release line: Firefox 150 or applicable ESR fix.
  • Update Thunderbird to Thunderbird 150 or Thunderbird 140.10 where applicable.
  • Apply relevant Red Hat security advisories for packaged Mozilla products.
  • Check Mozilla and OS-vendor guidance for environment-specific remediation details.
  • Prioritize managed desktops, VDI images, and mail-client deployments.

Validation and detection

  • Inventory Firefox, Firefox ESR, and Thunderbird versions across endpoints.
  • Confirm installed versions meet or exceed Mozilla’s fixed releases.
  • For Red Hat systems, verify relevant RHSA updates are applied.
  • Check for unmanaged portable or user-installed Mozilla applications.
  • Run vulnerability scanning after updates to confirm closure.
Prepared
Confidence
high
Sources
11

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-824: 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.

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cwe · low confidence lookup

CWE-908: 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-2026-6749 mapping review

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

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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:H/I:N/A:N

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
37Source 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:H/I:N/A:N3.93.6CISA-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-2026-6749Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

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: Information disclosure due to uninitialized memory in the Graphics: Canvas2D component
other:Red Hat severity ratingcvssV3_1
  • 2026-04-21T14:02:17.294Z: Reported to Red Hat.
  • 2026-04-21T12:40:46.800Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
MozillaFirefox115.35, 140.10, 150Listed
MozillaThunderbird140.10, 150Listed
Weakness

CWE details

CWE-824CWE-908

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

CWE-824 · source CWE mapping

Access of Uninitialized Pointer

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

Open CWE intelligenceSame-CWE CVEs
CWE-908 · source CWE mapping

Use of Uninitialized Resource

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

Open CWE intelligenceSame-CWE CVEs