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CVE Record

CVE-2026-8973: Memory safety bugs fixed in Firefox 151

Memory safety bugs present in Firefox 150. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 151 and Thunderbird 151.

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This is a high-severity Mozilla memory safety issue affecting Firefox 150-era code, fixed in Firefox 151 and Thunderbird 151. Mozilla says some bugs showed memory corruption and could potentially be exploited for arbitrary code execution with enough effort. User interaction is required, so exposure is mainly through browsing or email content handled by affected Mozilla software.

Executive priority

Treat this as a near-term browser and email client patching priority. It is high impact but not currently documented as exploited in the provided sources.

Technical view

CVE-2026-8973 groups memory safety bugs with CWE-119 and CWE-787 characteristics. The CVSS 3.1 score is 8.8 with network attack vector, low complexity, no privileges, required user interaction, and high confidentiality, integrity, and availability impact. The bundle states the issue was fixed in Firefox 151 and Thunderbird 151.

Likely exposure

Organizations are most exposed where Firefox or Thunderbird is installed but not updated to version 151 or later. The provided affected-version metadata is internally inconsistent, so validate against Mozilla advisories and installed versions.

Exploitation context

The source bundle does not identify active exploitation, and KEV is false. Mozilla's wording indicates memory corruption evidence and a presumption that arbitrary code execution may be possible with enough effort.

Researcher notes

Avoid assuming a public exploit or a specific vulnerable code path from this bundle. The Bugzilla list suggests multiple underlying bugs, but detailed exploitability and per-bug exposure are not established here.

Mitigation direction

  • Update Firefox to version 151 or later.
  • Update Thunderbird to version 151 or later.
  • Check Mozilla advisories for product-specific release guidance.
  • For Linux fleets, check vendor package advisories such as Red Hat.
  • Prioritize managed endpoints used for web browsing or email.

Validation and detection

  • Inventory installed Firefox and Thunderbird versions across endpoints.
  • Confirm Firefox reports version 151 or later.
  • Confirm Thunderbird reports version 151 or later.
  • Review endpoint management or package manager compliance status.
  • Monitor Mozilla, Red Hat, and CVE records for later corrections.
Prepared
Confidence
medium
Sources
8

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-119: 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-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.

Open ATT&CK lookup
description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. 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-2026-8973 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
8.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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
7Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical 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
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H2.85.9CISA-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

8.8High
CVSS 3.1 vector shape for CVE-2026-8973Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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: Memory safety bugs fixed in Firefox 151
other:Red Hat severity ratingcvssV3_1
  • 2026-05-19T14:02:39.923Z: Reported to Red Hat.
  • 2026-05-19T12:30:21.692Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
MozillaFirefox151Listed
MozillaThunderbird151Listed
Weakness

CWE details

CWE-119CWE-787

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