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Full vulnerability report · 2019
CVE-2019-9791High confidence

Mozilla Thunderbird: Access of Resource Using Incompatible Type ('Type Confusion')

Mozilla · Thunderbird

9.8CriticalCVSS 3.1
Recommended action
Within 72 hours

Critical technical impact with a remotely reachable, unauthenticated path and a public exploit reference; no CISA KEV confirmation is currently recorded.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 19.91% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • 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 Thunderbird and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  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.60.6.1-r0Alpine Security Database ↗Source updated 22 Oct 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.60.6.1-r0Alpine Security Database ↗Source updated 22 Oct 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.60.6.1-r0Alpine Security Database ↗Source updated 22 Oct 2026
Debian trixietrixie · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.60.6.0esr-1Debian Security Tracker ↗Source updated 23 Oct 2026
Debian trixietrixie · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:60.6.1-1Debian Security Tracker ↗Source updated 23 Oct 2026
Debian bookwormbookworm · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.60.6.0esr-1Debian Security Tracker ↗Source updated 23 Oct 2026
Debian bookwormbookworm · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:60.6.1-1Debian Security Tracker ↗Source updated 23 Oct 2026
Debian forkyforky · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.60.6.0esr-1Debian Security Tracker ↗Source updated 23 Oct 2026
Debian forkyforky · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:60.6.1-1Debian Security Tracker ↗Source updated 23 Oct 2026
Debian sidsid · sourcefirefoxVendor fix publishedDebian records a fixed source-package version for this release.66.0-1Debian Security Tracker ↗Source updated 23 Oct 2026
Debian sidsid · sourcefirefox-esrVendor fix publishedDebian records a fixed source-package version for this release.60.6.0esr-1Debian Security Tracker ↗Source updated 23 Oct 2026
Debian sidsid · sourcethunderbirdVendor fix publishedDebian records a fixed source-package version for this release.1:60.6.1-1Debian Security Tracker ↗Source updated 23 Oct 2026
Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2019-9791 · CSAF 2.0 · revision 26 · interimSUSE Product Security TeamCVE-2019-9791
24 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • MozillaFirefox as component of SUSE CaaS Platform 4.0
  • MozillaFirefox-devel as component of SUSE CaaS Platform 4.0
  • MozillaFirefox-translations-common as component of SUSE CaaS Platform 4.0
  • MozillaFirefox-translations-other as component of SUSE CaaS Platform 4.0
  • MozillaFirefox as component of SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS
  • MozillaFirefox-devel as component of SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS
  • MozillaFirefox-translations-common as component of SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS
  • MozillaFirefox-translations-other as component of SUSE Linux Enterprise High Performance Computing 15 SP1-LTSS
  • MozillaFirefox as component of SUSE Linux Enterprise High Performance Computing 15 SP1
  • MozillaFirefox-devel as component of SUSE Linux Enterprise High Performance Computing 15 SP1
  • MozillaFirefox-translations-common as component of SUSE Linux Enterprise High Performance Computing 15 SP1
  • MozillaFirefox-translations-other as component of SUSE Linux Enterprise High Performance Computing 15 SP1
Summary
The type inference system allows the compilation of functions that can cause type confusions between arbitrary objects when compiled through the IonMonkey just-in-time (JIT) compiler and when the constructor function is entered through on-stack replacement (OSR). This allows for possible arbitrary reading and writing of objects during an exploitable crash. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.
Remediation
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
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-2019-19153

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 72 hours

Critical technical impact with a remotely reachable, unauthenticated path and a public exploit reference; no CISA KEV confirmation is currently recorded.

Patch available
01

What, why and how

The type inference system allows the compilation of functions that can cause type confusions between arbitrary objects when compiled through the IonMonkey just-in-time (JIT) compiler and when the constructor function is entered through on-stack replacement (OSR). This allows for possible arbitrary reading and writing of objects during an exploitable crash. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

What

The type inference system allows the compilation of functions that can cause type confusions between arbitrary objects when compiled through the IonMonkey just-in-time (JIT) compiler and when the constructor function is entered through on-stack replacement (OSR). This allows for possible arbitrary reading and writing of objects during an exploitable crash. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

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 or user interaction. If successful, the issue may disrupt the affected service.

What

The type inference system allows the compilation of functions that can cause type confusions between arbitrary objects when compiled through the IonMonkey just-in-time (JIT) compiler and when the constructor function is entered through on-stack replacement (OSR). This allows for possible arbitrary reading and writing of objects during an exploitable crash. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.

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 or 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.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

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
None
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:N/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.UINoneUser interaction: No action by another user is required.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-843Public exploit reference
A

Official authority intelligence

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

CERT-FR · French · CERTFR-2019-AVI-118Multiples vulnérabilités dans Mozilla Firefox

urité de l'éditeur pour l'obtention des correctifs (cf. section Documentation). Documentation Bulletin de sécurité Mozilla mfsa2019-07 du 19 mars 2019 https://www.mozilla.org/en-US/security/advisories/mfsa2019-07/ Bulletin de sécurité Mozilla mfsa2019-08 du 19 mars 2019 https://www.mozilla.org/en-US/security/advisories/mfsa2019-08/ Référence CVE CVE-2018-18506 https://www.cve.org/CVERecord?id=CVE-2018-18506 Référence CVE CVE-2019-9788 https://www.cve.org/CVERecord?id=CVE-2019-9788 Référence CVE CVE-2019-9789 https://www.cve.org/CVERecord?id=CVE-2019-9789 Référence CVE CVE-2019-9790 https://www.cve.org/CVERecord?id=CVE-2019-9790 Référence CVE CVE-2019-9791 https://www.cve.org/CVERecord?id=CVE-2019-9791 Référence CVE CVE-2019-9792 https://www.cve.org/CVERecord?id=CVE-2019-9792 Référence CVE CVE-2019-9793 https://www.cve.org/CVERecord?id=CVE-2019-9793 Référence CVE CVE-2019-9794 https://www.cve.org/CVERecord?id=CVE-2019-9794 Référence CVE CVE-2019-9795 https://www.cve.org/CVERecord?id=CVE-2019-9795 Référence CVE CVE-2019-9796 https://www.cve.org/CVERecord?id=CVE-2019-9796 Référence CVE CVE-2019-9797 https://www.cve.org/CVERecord?id=CVE-2019-9797 Référence CVE CVE-2019-9798 https://www.cve.org/CVERecord?id=CVE-2019-9798 Référence CVE CVE-2019-9799 https://www.cve.org/CVERecord?id=CVE-2019-9799 Ré

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2019-004166Thunderbird および Firefox における型の取り違えに関する脆弱性

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

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.
Patch available
Affected
Fixed
No fixed version is explicitly recorded in the structured CVE data.
Action
To install this SUSE Security Update use the SUSE recommended installation methods like YaST online_update or "zypper patch".
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 26 Apr 2019 · Last source change 4 Aug 2024, 22:01 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-2019-19153
Product sourceVendor CSAF · SUSE Product Security Team
Remediation sourceVendor CSAF · SUSE Product Security Team
CWE sourceNIST NVD
NVD statusNVD modified after enrichment

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

Material change intelligence

What changed after publication

View recent updates ↗
  1. Remediation statusRemediation status changed from Awaiting fix to Mitigation available.
    Before
    Awaiting fix
    After
    Mitigation available
    SUSE Product Security Team ↗
  2. ENISA EUVD mappingEUVD-2019-19153 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2019-19153"}
    ENISA EUVD ↗
  3. Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: bugzilla.mozilla.org/show_bug.cgi?id=1530958; added vendor advisory: mozilla.org/mfsa2019-07; removed vendor advisory: access.redhat.com/RHSA-2019:0966; removed vendor advisory: access.redhat.com/RHSA-2019:1144; 2 further additions.
    Before
    vendor advisory: access.redhat.com/RHSA-2019:0966 · vendor advisory: access.redhat.com/RHSA-2019:1144
    After
    vendor advisory: bugzilla.mozilla.org/show_bug.cgi?id=1530958 · vendor advisory: mozilla.org/mfsa2019-07 · vendor advisory: mozilla.org/mfsa2019-08 · 1 more references
    mozilla.org ↗
  4. Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.
    Before
    No public exploit
    After
    Public exploit reference
    bugzilla.mozilla.org ↗
  5. SeveritySeverity changed from Unknown to Critical.
    Before
    Unknown
    After
    Critical
    NIST NVD ↗
  6. CVSS scoreCVSS score changed from not recorded to 9.8 (CVSS 3.1 · NIST NVD · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).
    Before
    not recorded
    After
    9.8 (CVSS 3.1 · NIST NVD · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
    NIST NVD ↗
  7. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Remediation guidance recorded
ENISA EUVD · EUVD-2019-19153↗SUSE Product Security Team security advisory↗CVE authority or vendor reference↗Vendor advisory↗Vendor advisory↗Public exploit reference↗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-2019-9791 · cve.blacktree.nl