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CVE Record

CVE-2026-4697: Incorrect boundary conditions in the Audio/Video: Web Codecs component

Incorrect boundary conditions in the Audio/Video: Web Codecs component. This vulnerability was fixed in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-4697 is a high-severity Mozilla Web Codecs flaw that can cause a denial of service. The supplied record says Mozilla fixed it in Firefox 149, Firefox ESR 140.9, Thunderbird 149, and Thunderbird 140.9. No provided source shows confirmed active exploitation.

Executive priority

Treat as a timely patching priority for user workstations and Linux fleets. The known impact is availability, not data theft, but browsers and mail clients are widely exposed software with frequent external content handling.

Technical view

The issue is described as incorrect boundary conditions in the Audio/Video Web Codecs component, mapped to CWE-754 and CWE-787. CVSS 3.1 is 7.5 with network attack vector, low complexity, no privileges, no user interaction, and high availability impact only.

Likely exposure

Exposure is most likely on systems running Mozilla Firefox, Firefox ESR, or Thunderbird before the fixed versions named in the source bundle. Red Hat references indicate downstream Linux packages may also require vendor errata review.

Exploitation context

The CVE metadata supports remotely reachable denial-of-service risk, but not confidentiality or integrity impact. The bundle marks KEV as false and provides no cited evidence of exploitation in the wild.

Researcher notes

The source bundle does not include bug-level technical details beyond boundary-condition handling in Web Codecs and CWE mappings. Avoid assuming code execution or active exploitation without additional vendor evidence.

Mitigation direction

  • Update Firefox to 149 or later where applicable.
  • Update Firefox ESR to 140.9 or later.
  • Update Thunderbird to 149 or 140.9 or later.
  • Review Red Hat advisories for affected enterprise Linux packages.
  • Check Mozilla advisories for platform-specific fixed builds.

Validation and detection

  • Inventory installed Firefox, Firefox ESR, and Thunderbird versions.
  • Confirm managed endpoints meet or exceed the fixed Mozilla versions.
  • Check Red Hat errata status for relevant Linux hosts.
  • Verify browser and mail-client updates are enforced by endpoint management.
  • Monitor vendor advisories for any revised exploit or impact information.
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-754: 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-787: 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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cve · low confidence lookup

CVE-2026-4697 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: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
34Source 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:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-4697Attack 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: Incorrect boundary conditions in the Audio/Video: Web Codecs component
other:Red Hat severity ratingcvssV3_1
  • 2026-03-24T13:02:22.985Z: Reported to Red Hat.
  • 2026-03-24T12:30:27.383Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
MozillaFirefox140.9, 149Listed
MozillaThunderbird140.9, 149Listed
Weakness

CWE details

CWE-754CWE-787

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

CWE-754 · source CWE mapping

Improper Check for Unusual or Exceptional Conditions

Improper Check for Unusual or Exceptional Conditions represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-787 · source CWE mapping

Out-of-bounds Write

Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs