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CVE Record

CVE-2026-2762: Integer overflow in the JavaScript: Standard Library component

Integer overflow in the JavaScript: Standard Library component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

CriticalCVSS 9.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

Mozilla fixed a critical integer overflow in the JavaScript standard library used by Firefox and Thunderbird. The source bundle rates it CVSS 9.8, meaning compromise could be severe if vulnerable builds are present. Patch urgency is high, but the provided sources do not show confirmed active exploitation.

Executive priority

Treat this as an urgent browser and email-client patching issue. The severity score is critical and impact could be broad, but current source evidence does not support saying it is being actively exploited. Focus on fast inventory, patch deployment, and exception tracking.

Technical view

CVE-2026-2762 is a CWE-190 integer overflow in Mozilla's JavaScript Standard Library component. The CVSS v3.1 vector is network, low complexity, no privileges, no user interaction, unchanged scope, and high confidentiality, integrity, and availability impact. Mozilla lists fixes in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Likely exposure

Exposure is likely wherever vulnerable Mozilla Firefox or Thunderbird builds are installed, including downstream Linux packages covered by Red Hat advisories. The bundle does not identify exact vulnerable version ranges beyond naming fixed releases, so asset owners should verify installed versions against vendor guidance.

Exploitation context

The bundle marks KEV as false and provides no cited evidence of active exploitation. Technical exploitability is still concerning because the CVSS vector indicates network reachability, low complexity, no privileges, and no user interaction. Public technical detail is limited in the provided sources.

Researcher notes

Key gaps are the absence of detailed vulnerable version ranges, exploit mechanics, and observed exploitation evidence in the provided bundle. Researchers should rely on Mozilla advisories, the CVE record, Bugzilla entry, and Red Hat VEX or errata for authoritative affected-package status.

Mitigation direction

  • Update Firefox to 148 or Firefox ESR to 140.8 where applicable.
  • Update Thunderbird to 148 or Thunderbird 140.8 where applicable.
  • Apply relevant Red Hat security advisories for managed Linux packages.
  • Check Mozilla and Red Hat guidance for platform-specific package status.
  • Prioritize high-risk user groups and systems with broad web or email exposure.

Validation and detection

  • Inventory Firefox and Thunderbird installations across endpoints and managed images.
  • Confirm installed versions meet or exceed the fixed releases named by Mozilla.
  • Verify Red Hat errata are applied on affected Red Hat-managed systems.
  • Review vulnerability scanner results against Mozilla and Red Hat source advisories.
  • Document exceptions where vendor guidance says a platform is not affected.
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-190: 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-2026-2762 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
Critical
CVSS
9.8 (3.1)
Known Exploited
No
Published

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

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
9.8CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9CISA-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

9.8Critical
CVSS 3.1 vector shape for CVE-2026-2762Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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: Integer overflow in the JavaScript: Standard Library component
other:Red Hat severity ratingcvssV3_1
  • 2026-02-24T14:03:31.898Z: Reported to Red Hat.
  • 2026-02-24T13:33:01.761Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
MozillaFirefox140.8, 148Listed
MozillaThunderbird140.8, 148Listed
Weakness

CWE details

CWE-190

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

CWE-190 · source CWE mapping

Integer Overflow or Wraparound

Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs