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NVD / CVE Program· CNA mozilla

CVE-2026-12301: Memory safety bug fixed in Thunderbird 152

MediumCVSS 5.3 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 21/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.25% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: MozillaFirefox (openSUSE:Tumbleweed) 152.0-1.1.

Low priority for now. Upgrade to MozillaFirefox (openSUSE:Tumbleweed) 152.0-1.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Memory safety bug fixed in Thunderbird 152. This vulnerability was fixed in Firefox 152 and Thunderbird 152.

Published
Jun 16, 2026
Updated
Oct 26, 2026
EPSS
0.2% · 16th percentile

Report tools

JSON

Action score

21

Monitor

Low priority for now.

CVSS
21 / 40 · 5.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-12301

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
mozillafirefox
mozillathunderbird

Versions reported by the vendor

Affected version ranges reported by the assigning authority (mozilla). Independent of NVD's CPE analysis and usually ahead of it.

  • Mozilla Firefox

    • 152 and laternot affected · rpm

  • Mozilla Thunderbird

    • 152 and laternot affected · rpm

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • mozilla firefoxbefore 152.0.0
  • mozilla thunderbirdbefore 152.0.0

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
openSUSE:TumbleweedMozillaFirefoxbefore 152.0-1.1152.0-1.1

Same product

mozilla: all records

Other highest-scoring records for the same primary product.

  • CVE-2010-3765Mozilla Firefox 3.5.x through 3.5.14 and 3.6.x through 3.6.11, Thunderbird 3.1.6 before 3.1.6 and 3.0.x before 3.0.10, and SeaMonkey 2.x…KEV
    94Now
  • CVE-2019-11708Insufficient vetting of parameters passed with the Prompt:Open IPC message between child and parent processes can result in the…KEV
    87Now
  • CVE-2015-4495The PDF reader in Mozilla Firefox before 39.0.3, Firefox ESR 38.x before 38.1.1, and Firefox OS before 2.2 allows remote attackers to…KEV
    86Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-12299Jun 16, 2026 · JIT miscompilation in the DOM: Core & HTML component
    21Monitor
  • ← EarlierCVE-2026-12300Jun 16, 2026 · Memory safety bug fixed in Thunderbird 152
    21Monitor
  • Later →CVE-2026-12302Jun 16, 2026 · Mitigation bypass in the DOM: Security component
    26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
opensuse:MozillaFirefox152.0-1.1 · openSUSE:TumbleweedPackage registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2026-1636735 days apartSandbox escape due to invalid pointer in the Disability Access APIs component
    40Plan
  • CVE-2026-2776112 days apartSandbox escape due to incorrect boundary conditions in the Telemetry component in External Software
    40Plan
  • CVE-2026-2778112 days apartSandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component
    40Plan
  • CVE-2026-1635035 days apartIncorrect boundary conditions in the Audio/Video: cubeb component
    39Monitor
  • CVE-2026-1635735 days apartIncorrect boundary conditions in the Graphics component
    39Monitor
  • CVE-2026-1636035 days apartMemory safety bugs fixed in Thunderbird ESR 140.13 and Thunderbird 153
    39Monitor

Not on record for this CVE: EPSS history · patch commit or PR link · public bounty program.

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
low · data can be read
Integrity
none
Availability
none
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

References

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records