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CVE Record

CVE-2026-12290: Memory safety bug fixed in Firefox 152

Memory safety bug fixed in Firefox 152. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12.

HighCVSS 8.1Not 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. A user would likely need to interact with malicious web or email content, but successful exploitation could expose sensitive data or let an attacker change browser or mail-client state. Mozilla lists fixed releases for Firefox, Firefox ESR, and Thunderbird.

Executive priority

Treat this as a near-term endpoint patching priority. The issue is high severity with potential confidentiality and integrity impact, but current provided evidence does not support emergency active-exploitation handling.

Technical view

CVE-2026-12290 is described as a memory safety bug with CWE-119 and CWE-823 classifications. CVSS 3.1 is 8.1: network reachable, low complexity, no privileges, user interaction required, unchanged scope, high confidentiality and integrity impact, and no availability impact.

Likely exposure

Organizations are exposed where Firefox, Firefox ESR, or Thunderbird remain below the fixed release lines named by Mozilla, including distro-managed packages covered by Red Hat advisories. Exposure is highest on endpoints where users browse untrusted sites or process external email content.

Exploitation context

The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The CVSS vector indicates exploitation requires user interaction over a network path, consistent with malicious web or email content risk, but the bundle does not provide exploit details.

Researcher notes

The public bundle provides limited root-cause detail beyond memory safety and CWE mapping. Avoid assuming exploitability beyond the CVSS vector. Bugzilla and Mozilla advisories are the primary sources; Red Hat materials confirm downstream tracking and errata.

Mitigation direction

  • Update Firefox to 152, ESR 140.12, ESR 115.37, or later as applicable.
  • Update Thunderbird to 152, 140.12, or later as applicable.
  • Apply relevant Red Hat security errata for Mozilla packages where Red Hat builds are used.
  • Check Mozilla and OS vendor guidance for any environment-specific mitigations or package names.

Validation and detection

  • Inventory Firefox, Firefox ESR, and Thunderbird versions across managed endpoints.
  • Confirm deployed versions meet or exceed the fixed releases listed by Mozilla.
  • For Red Hat systems, verify the applicable RHSA packages are installed.
  • Review vulnerability scanner results for CVE-2026-12290 after patch deployment.
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-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.

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cwe · low confidence lookup

CWE-823: 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-2026-12290 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
8.1 (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:N

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
22Source 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
8.1CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N2.85.2CISA-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

8.1High
CVSS 3.1 vector shape for CVE-2026-12290Attack 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:N

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 bug fixed in Thunderbird ESR 140.12
other:Red Hat severity ratingcvssV3_1
  • 2026-06-16T14:01:07.473Z: Reported to Red Hat.
  • 2026-06-16T11:52:23.998Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
MozillaFirefox115.37, 140.12, 152Listed
MozillaThunderbird140.12, 152Listed
Weakness

CWE details

CWE-119CWE-823

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

CWE-119 · source CWE mapping

Improper Restriction of Operations within the Bounds of a Memory Buffer

Improper Restriction of Operations within the Bounds of a Memory Buffer represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-823 · source CWE mapping

Use of Out-of-range Pointer Offset

Use of Out-of-range Pointer Offset represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs