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CVE Record

CVE-2026-2793: Memory safety bugs fixed in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148

Memory safety bugs present in Firefox ESR 115.32, Firefox ESR 140.7, Thunderbird ESR 140.7, Firefox 147 and Thunderbird 147. 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 148, Firefox ESR 115.33, 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

CVE-2026-2793 is a critical Mozilla memory-safety vulnerability group affecting older Firefox and Thunderbird releases. Mozilla fixed it in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird ESR 140.8. Mozilla says some bugs showed memory corruption and could potentially allow arbitrary code execution with enough effort.

Executive priority

Prioritize remediation in the next patch cycle or sooner for high-risk user populations. The vulnerability is critical, remotely reachable by CVSS, and tied to possible code execution, but the provided sources do not confirm active exploitation.

Technical view

The source describes CWE-787 memory corruption in Firefox ESR 115.32, Firefox ESR 140.7, Thunderbird ESR 140.7, Firefox 147, and Thunderbird 147. CVSS 3.1 is 9.8, network attack vector, low complexity, no privileges, and high confidentiality, integrity, and availability impact. Red Hat also published advisories and VEX data for packaged exposure.

Likely exposure

Organizations are likely exposed where managed endpoints, servers, or Red Hat systems still run the vulnerable Firefox or Thunderbird versions named by Mozilla. Exposure should be assessed through software inventory, package state, and browser/email client version reporting.

Exploitation context

The bundle does not show CISA KEV listing or cite active exploitation. Mozilla states there was evidence of memory corruption and that arbitrary code execution may be possible with enough effort. Treat as urgent, but not as confirmed exploited from the provided evidence.

Researcher notes

This appears to be a Mozilla memory-safety rollup with limited public bug detail. Avoid assuming a single trigger path. Focus validation on version/package state and advisory mapping, especially Red Hat backports where package versions may not match upstream Mozilla numbering.

Mitigation direction

  • Update Firefox to 148, ESR 115.33, or ESR 140.8 as applicable.
  • Update Thunderbird to 148 or ESR 140.8 as applicable.
  • Apply relevant Red Hat security advisories for packaged Mozilla components.
  • Prioritize endpoints handling web browsing, email, or untrusted content.
  • Check Mozilla and Red Hat guidance for platform-specific backports.

Validation and detection

  • Inventory Firefox and Thunderbird versions across managed assets.
  • Confirm vulnerable versions are no longer present after updates.
  • Review Red Hat package advisory status where applicable.
  • Verify endpoint management reports show fixed Mozilla versions.
  • Track exceptions for unsupported or manually installed browser clients.
Prepared
Confidence
high
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-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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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.

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cve · low confidence lookup

CVE-2026-2793 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
35Source 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
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-2026-2793Attack 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
other:ssvccvssV3_1
redhat-SADPfirefox: thunderbird: Memory safety bugs fixed in Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird ESR 140.8, Firefox 148 and Thunderbird 148
other:Red Hat severity ratingcvssV3_1
  • 2026-02-24T14:02:07.299Z: Reported to Red Hat.
  • 2026-02-24T13:33:23.571Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
MozillaFirefox115.33, 140.8, 148Listed
MozillaThunderbird140.8, 148Listed
Weakness

CWE details

CWE-787

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

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.

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