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Full vulnerability report · 2019
CVE-2019-11707High confidence

Mozilla Firefox and Thunderbird Type Confusion Vulnerability

Mozilla · Firefox and Thunderbird

8.8HighCVSS 3.1
Recommended action
Protect now

CISA confirms exploitation in the wild and lists 2022-06-13 as the remediation due date.

Fix not verified
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Critical, raised one band.upgradedsince 23 May 2022

Evidence used

  • CISA confirms exploitation in the wild.
  • EPSS is 37.70% for the current model date.

Compensating controls

  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs Mozilla Firefox and Thunderbird and falls inside the recorded affected range.
  2. Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Distribution package intelligence

Release-specific package status

Alpine, Debian findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.

12 package states
Repository candidate not checked

A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.

Distribution releaseSource packageVendor stateFixed versionEvidence
Alpine v3.23v3.23 · communityfirefox-esrVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.60.7.1-r0Alpine Security Database ↗Source updated 11 Sep 2026
Alpine v3.22v3.22 · communityfirefox-esrVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.60.7.1-r0Alpine Security Database ↗Source updated 11 Sep 2026
Alpine v3.21v3.21 · communityfirefox-esrVendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected.60.7.1-r0Alpine Security Database ↗Source updated 19 Aug 2026
Debian trixietrixie · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.60.7.1esr-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian trixietrixie · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:60.7.2-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.60.7.1esr-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian bookwormbookworm · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:60.7.2-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.60.7.1esr-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian forkyforky · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:60.7.2-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcefirefoxVendor fix publishedDebian records a fixed source-package version for this release.67.0.3-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.60.7.1esr-1Debian Security Tracker ↗Source updated 6 Oct 2026
Debian sidsid · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:60.7.2-1Debian Security Tracker ↗Source updated 6 Oct 2026
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2019-3377

CISA KEV mirrored by ENISA

A type confusion vulnerability can occur when manipulating JavaScript objects due to issues in Array.pop. This can allow for an exploitable crash. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 60.7.1, Firefox < 67.0.3, and Thunderbird < 60.7.2.

EUVD state
Present in the current official mapping
Known exploitation
Recorded by ENISA since 23 May 2022. Evidence sources: cisa_kev.
ENISA score
8.8 · CVSS 3.1
Advisory evidence
15 linked advisory records
Explicit mitigation evidence

Only statements that explicitly mention a fix, patch, update, workaround or mitigation are shown here.

  • csaf_redhat · RHSA-2019:1696Red Hat Security Advisory: firefox security update
  • csaf_suse · SUSE-SU-2019:1683-1Security update for MozillaThunderbird
  • csaf_opensuse · openSUSE-SU-2019:1606-1Security update for MozillaThunderbird
  • csaf_redhat · RHSA-2019:1626Red Hat Security Advisory: thunderbird security update
  • csaf_redhat · RHSA-2019:1623Red Hat Security Advisory: thunderbird security update
  • csaf_redhat · RHSA-2019:1624Red Hat Security Advisory: thunderbird security update
  • csaf_opensuse · openSUSE-SU-2019:1664-1Security update for MozillaThunderbird
  • csaf_opensuse · openSUSE-SU-2019:1593-1Security update for MozillaFirefox
  • csaf_redhat · RHSA-2019:1604Red Hat Security Advisory: firefox security update
  • csaf_suse · SUSE-SU-2019:14124-1Security update for MozillaFirefox
  • csaf_suse · SUSE-RU-2019:1625-1Recommended update for MozillaFirefox
  • csaf_redhat · RHSA-2019:1603Red Hat Security Advisory: firefox security update
  • csaf_suse · SUSE-SU-2019:1629-1Security update for MozillaFirefox
Recommended actionProtect now

CISA confirms exploitation in the wild and lists 2022-06-13 as the remediation due date.

Fix not verified
01

What, why and how

Mozilla Firefox and Thunderbird contain a type confusion vulnerability that can occur when manipulating JavaScript objects due to issues in Array.pop, allowing for an exploitable crash.

What

Mozilla Firefox and Thunderbird contain a type confusion vulnerability that can occur when manipulating JavaScript objects due to issues in Array.pop, allowing for an exploitable crash.

Why

The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may disrupt the affected service.

What

Mozilla Firefox and Thunderbird contain a type confusion vulnerability that can occur when manipulating JavaScript objects due to issues in Array.pop, allowing for an exploitable crash.

Why

The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Confirmed in the wild

CISA added this CVE to its Known Exploited Vulnerabilities catalogue on 2022-05-23.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Access of Resource Using Incompatible Type ('Type Confusion') → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
Required interaction required
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-843 ↗

CWE-843: Access of Resource Using Incompatible Type ('Type Confusion'). The product allocates or initializes a resource such as a pointer, object, or variable using one type, but it later accesses that resource using a type that is incompatible with the original type.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UIRequiredUser interaction: Another user must perform an action for exploitation to succeed.SUnchangedScope: The security impact remains within the vulnerable component's authority.CHighConfidentiality impact: A successful attack can cause a major loss.IHighIntegrity impact: A successful attack can cause a major loss.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
NetworkUnauthenticatedDenial of serviceCWE-843CISA KEV
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2019-3377Known-exploited evidence recorded

A type confusion vulnerability can occur when manipulating JavaScript objects due to issues in Array.pop. This can allow for an exploitable crash. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 60.7.1, Firefox < 67.0.3, and Thunderbird < 60.7.2.

Official EUVD record ↗
Canadian Centre for Cyber Security · English · AV19-119Mozilla security advisory

On 18 June 2019 Mozilla released security updates to address a vulnerability in Firefox and Firefox ESR. The vulnerability, tracked as CVE-2019-11707, could allow a remote actor to take control of the affected system. Active exploitation of this vulnerability has been reported. CCCS encourages users and administrators to review the Mozilla Foundation Security Advisories webpage and apply the necessary updates:

Official advisory ↗
CERT-FR · French · CERTFR-2019-AVI-287Multiples vulnérabilités dans Mozilla Firefox et Thunderbird

De multiples vulnérabilités ont été découvertes dans Mozilla Firefox et Thunderbird. Elles permettent à un attaquant de provoquer une exécution de code arbitraire et un contournement de la politique de sécurité.

Official advisory ↗
CERT-FR · French · CERTFR-2019-AVI-280Vulnérabilité dans Mozilla Firefox

Une vulnérabilité a été découverte dans Mozilla Firefox. Elle permet à un attaquant de provoquer une exécution de code arbitraire à distance et un déni de service à distance.

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2019-006899Firefox および Thunderbird における型の取り違えに関する脆弱性

Firefox および Thunderbird には、型の取り違えに関する脆弱性が存在します。

Official advisory ↗
KISA KrCERT/CC · Korean · KNVD-5034Firefox 원격코드실행 취약점 보안 업데이트 권고

Firefox에서 type confusion 및 IPC 메시지에 대한 파라미터 검증이 미흡하여 발생하는 원격코드 실행 취약점(CVE-2019-11707, 11708) [1], [2]

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix not verified
Affected
  • Firefox ESR: unspecified < 60.7.1
  • Firefox: unspecified < 67.0.3
  • Thunderbird: unspecified < 60.7.2
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
No verified patch reference is present in the current structured sources. Check the vendor advisory before making a change.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 23 Jul 2019 · Last source change 21 Oct 2025, 23:45 UTC · CWE-843 · Access of Resource Using Incompatible Type ('Type Confusion')

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-01
European sourceENISA EUVD · EUVD-2019-3377
Product sourceCISA KEV
Remediation sourceCVE/CNA references
CWE sourceCISA ADP
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. ENISA known-exploited stateENISA EUVD now records this CVE in its known-exploited dataset.
    Before
    not listed in ENISA EUVD known-exploited dataset
    After
    listed in ENISA EUVD known-exploited dataset (EUVD-2019-3377)
    ENISA EUVD ↗
  2. ENISA EUVD mappingEUVD-2019-3377 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2019-3377"}
    ENISA EUVD ↗
  3. Affected versionsThe structured affected or fixed version information changed.
    Before
    unspecified < 60.7.1; unspecified < 67.0.3; unspecified < 60.7.2 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    After
    Firefox ESR: unspecified < 60.7.1; Firefox: unspecified < 67.0.3; Thunderbird: unspecified < 60.7.2 · Fixed: No fixed version is explicitly recorded in the structured CVE data.
    CNA ↗
  4. Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: bugzilla.mozilla.org/show_bug.cgi?id=1544386; added vendor advisory: mozilla.org/mfsa2019-18; removed vendor advisory: security.gentoo.org/201908-12; 1 further additions.
    Before
    vendor advisory: security.gentoo.org/201908-12
    After
    vendor advisory: bugzilla.mozilla.org/show_bug.cgi?id=1544386 · vendor advisory: mozilla.org/mfsa2019-18 · vendor advisory: mozilla.org/mfsa2019-20
    mozilla.org ↗
  5. CVSS scoreCVSS scoring authority changed from CISA ADP to NIST NVD; the displayed base score remained 8.8.
    Before
    8.8 (CVSS 3.1 · CISA ADP · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)
    After
    8.8 (CVSS 3.1 · NIST NVD · CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)
    NIST NVD ↗
  6. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Added to CISA KEV
ENISA EUVD · EUVD-2019-3377↗CISA KEV record↗CVE authority or vendor reference↗Vendor advisory↗Vendor advisory↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2019-11707 · cve.blacktree.nl