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CVE-2026-100766· CVE.org (no NVD analysis yet)· CNA mozilla

Information disclosure in the Networking: JAR component

Noroxi assessment

Priority: Monitor (action score 17/100)

  • 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. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: firefox-esr (Debian:12) 153.4.0esr-1~deb12u1; thunderbird (Debian:12) 1:140.17.0esr-1~deb12u1; firefox-esr (Debian:13) 153.4.0esr-1~deb13u1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to firefox-esr (Debian:12) 153.4.0esr-1~deb12u1; thunderbird (Debian:12) 1:140.17.0esr-1~deb12u1; firefox-esr (Debian:13) 153.4.0esr-1~deb13u1 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

Information disclosure in the Networking: JAR component. This vulnerability was fixed in Firefox ESR 153.4, Thunderbird 157, Thunderbird 140.17, Thunderbird 153.4, Firefox 157, Firefox ESR 115.42, and Firefox ESR 140.17.

MediumCVSS 4.3 · v3.1—No exploit Fix available
Published
Sep 29, 2026
Updated
Oct 13, 2026
EPSS
0.2% · 15th percentile

Report tools

JSON

Action score

17

Monitor

Low priority for now.

CVSS
17 / 40 · 4.3 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
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-2026-100766

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

Affected versions

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

  • mozilla firefoxbefore 115.42.0
  • mozilla firefox116.0.0 and later · before 140.17.0
  • mozilla firefox141.0.0 and later · before 153.4.0
  • mozilla firefox154.0.0 and later · before 157.0.0
  • mozilla thunderbirdbefore 140.17.0
  • mozilla thunderbird141.0 and later · before 153.4.0
  • mozilla thunderbird154.0 and later · before 157.0

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

    • 115.42 and later · up to and including 115.*not affected · rpm
    • 140.17 and later · up to and including 140.*not affected · rpm
    • 153.4 and later · up to and including 153.*not affected · rpm
    • 157 and laternot affected · rpm

  • Mozilla Thunderbird

    • 140.17 and later · up to and including 140.*not affected · rpm
    • 153.4 and later · up to and including 153.*not affected · rpm
    • 157 and laternot affected · rpm

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12firefox-esrbefore 153.4.0esr-1~deb12u1153.4.0esr-1~deb12u1
Debian:12thunderbirdbefore 1:140.17.0esr-1~deb12u11:140.17.0esr-1~deb12u1
Debian:13firefox-esrbefore 153.4.0esr-1~deb13u1153.4.0esr-1~deb13u1
Debian:13thunderbirdbefore 1:140.17.0esr-1~deb13u11:140.17.0esr-1~deb13u1
Debian:14firefox-esrbefore 153.4.0esr-1153.4.0esr-1
Debian:14thunderbirdbefore 1:153.4.0esr-11:153.4.0esr-1
openSUSE:Leap 16.0MozillaFirefoxbefore 153.4.0-160000.1.1153.4.0-160000.1.1
openSUSE:Tumbleweedfirefox-esrbefore 153.4.0-1.1153.4.0-1.1
openSUSE:TumbleweedMozillaFirefoxbefore 157.0.1-1.1157.0.1-1.1
openSUSE:TumbleweedMozillaThunderbirdbefore 153.4.0-1.1153.4.0-1.1
SUSE:Linux Enterprise Module for Desktop Applications 15 SP7MozillaFirefoxbefore 153.4.0-150400.157.11.1153.4.0-150400.157.11.1
SUSE:Linux Enterprise Module for Package Hub 15 SP7MozillaThunderbirdbefore 153.4.0-150400.13.6.1153.4.0-150400.13.6.1
SUSE:Linux Enterprise Server 12 SP5-LTSSMozillaFirefoxbefore 153.4.0-118.11.1153.4.0-118.11.1
SUSE:Linux Enterprise Server 16.0MozillaFirefoxbefore 153.4.0-160000.1.1153.4.0-160000.1.1

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 befKEV
    94Now
  • CVE-2019-11708Insufficient vetting of parameters passed with the Prompt:Open IPC message between child and parent processes can result in the non-sandboxeKEV
    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 bypassKEV
    86Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-100764Sep 29, 2026 · Privilege escalation due to incorrect boundary conditions in the Graphics: WebGPU component
    35Monitor
  • ← EarlierCVE-2026-100765Sep 29, 2026 · Use-after-free in the JavaScript: WebAssembly component
    35Monitor
  • Later →CVE-2026-100767Sep 29, 2026 · Use-after-free in the Networking: Cache component
    35Monitor

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
debian:firefox-esr153.4.0esr-1~deb12u1 · Debian:12Package registry (OSV)
debian:firefox-esr153.4.0esr-1~deb13u1 · Debian:13Package registry (OSV)
debian:thunderbird1:140.17.0esr-1~deb12u1 · Debian:12Package registry (OSV)
opensuse:firefox-esr153.4.0-1.1 · openSUSE:TumbleweedPackage registry (OSV)
opensuse:MozillaFirefox153.4.0-160000.1.1 · openSUSE:Leap 16.0Package registry (OSV)
opensuse:MozillaFirefox157.0.1-1.1 · openSUSE:TumbleweedPackage registry (OSV)
opensuse:MozillaThunderbird153.4.0-1.1 · openSUSE:TumbleweedPackage registry (OSV)
suse:MozillaFirefox153.4.0-160000.1.1 · SUSE:Linux Enterprise Server 16.0Package registry (OSV)
suse:MozillaThunderbird153.4.0-150400.13.6.1 · SUSE:Linux Enterprise Module for Package Hub 15 SP7Package 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.

  1. Published
  2. Fix recorded+2 d
  3. TodayOct 21, 2026+22 d
EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

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-2026-1008100 days apartOther issue in the DevTools component
    39Monitor
  • CVE-2026-8413428 days apartOther issue in the Profile Backup component
    39Monitor
  • CVE-2026-1638770 days apartSite isolation issue in the Networking component
    39Monitor
  • CVE-2025-11710350 days apartCross-process information leaked due to malicious IPC messages
    39Monitor
  • CVE-2026-7498642 days apartSite isolation issue in the CSS Parsing and Computation component
    36Monitor
  • CVE-2025-11717350 days apartThe password edit screen was not hidden in Android card view
    36Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • A user must open a link or visit a page.
  • 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
Required
Scope
Unchanged
Confidentiality impact
Low
Integrity impact
None
Availability impact
None

Weakness class (CWE)

CWE-200 · Exposure of Sensitive Information to an Unauthorized Actor

CVSS vector

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

nvd-secondary

Root cause

The extension requests broader permissions than its function needs and sends the data it collects out for purposes beyond its stated function.

The bug in code

The whole CWE-200 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

json
{  "permissions": ["tabs", "<all_urls>"],  "background": { "service_worker": "analytics.js" }}

Fixed

json
{  "permissions": ["activeTab"],  "host_permissions": ["https://yildiz.example/*"]}

Attack context

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

Change log

  1. Fix✗ → ✓
  2. Exploit maturity— → none
  3. CVSS— → 4.3
  4. Severity— → medium
  5. SSVC exploitation— → none

For records you follow, these changes also arrive as notifications. →

References

Show all references (7 more)

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

All records