LiveActive security incident?Get immediate response
CVE Record

CVE-2026-0881: Sandbox escape in the Messaging System component

Sandbox escape in the Messaging System component. This vulnerability was fixed in Firefox 147 and Thunderbird 147.

CriticalCVSS 10Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

CVE-2026-0881 is a critical Mozilla sandbox escape in the Messaging System component. The source bundle says it was fixed in Firefox 147 and Thunderbird 147. A sandbox escape can let malicious activity break out of browser or mail-client restrictions, raising business risk if users run unpatched Mozilla software.

Executive priority

Treat this as urgent patch management for browser and mail-client fleets. The score and sandbox-escape class justify rapid remediation, even though the supplied evidence does not show confirmed active exploitation.

Technical view

The record describes a sandbox escape mapped to CWE-284 and CWE-693 with CVSS 3.1 score 10.0: network reachable, low complexity, no privileges, no user interaction, changed scope, and high confidentiality, integrity, and availability impact. Technical detail is limited in the supplied sources, and Bugzilla may restrict deeper implementation detail.

Likely exposure

Exposure is most likely where Firefox or Thunderbird deployments have not been updated to the fixed 147 release. The supplied bundle does not establish impact for ESR, mobile, downstream distro builds, or other Mozilla products, so validate against Mozilla and distributor advisories.

Exploitation context

The bundle marks KEV as false and provides no cited evidence of active exploitation. The CVSS vector indicates serious exploitability characteristics, but exploit availability, in-the-wild use, and triggering conditions are not established by the supplied sources.

Researcher notes

Public detail is sparse: the bundle names the component, weakness classes, CVSS vector, and fixed releases, but not root cause or exploit prerequisites. Avoid assuming affected variants beyond Firefox and Thunderbird until Mozilla, Red Hat, or other vendors clarify scope.

Mitigation direction

  • Update Firefox to Mozilla's fixed 147 release or later.
  • Update Thunderbird to Mozilla's fixed 147 release or later.
  • Check Mozilla advisories for product-specific update guidance.
  • Check Red Hat guidance if using distro-packaged Mozilla builds.
  • Prioritize managed updates on high-risk user workstations.

Validation and detection

  • Inventory installed Firefox and Thunderbird versions across endpoints.
  • Confirm deployed versions include Mozilla's 147 security fixes.
  • Review Mozilla MFSA advisories for affected product scope.
  • Review Red Hat CVE and VEX data for distro package status.
  • Document exceptions where updates cannot be applied promptly.
Prepared
Confidence
medium
Sources
6

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 · medium confidence lookup

CWE-284: Authorization and privilege behavior lookup

Authorization weaknesses can support privilege escalation and valid-account review, depending on exploit path. 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-693: 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
description · low confidence lookup

Privilege behavior lookup

The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-0881 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
Critical
CVSS
10 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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
7Source 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
10CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H3.96CISA-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

10Critical
CVSS 3.1 vector shape for CVE-2026-0881Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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: Sandbox escape in the Messaging System component
other:Red Hat severity ratingcvssV3_1
  • 2026-01-13T14:01:57.493Z: Reported to Red Hat.
  • 2026-01-13T13:30:55.122Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
MozillaFirefox147Listed
MozillaThunderbird147Listed
Weakness

CWE details

CWE-284CWE-693

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

CWE-284 · source CWE mapping

Improper Access Control

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

Open CWE intelligenceSame-CWE CVEs
CWE-693 · source CWE mapping

Protection Mechanism Failure

Protection Mechanism Failure represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs