Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 1.77% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2019
CVE-2019-9794High confidence
A vulnerability was discovered where specific command line arguments are not properly discarded during Firefox invocation as a shell handler for URLs
Mozilla · Thunderbird
9.8CriticalCVSS 3.0
Within 72 hours
Fix not verifiedCritical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityCritical→Operational priority:Critical, unchanged from published severity.unchanged
Compensating controls
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Mozilla Thunderbird and falls inside the recorded affected range.
- Recheck the vendor advisory before scheduling a change because no verified fixed version is currently retained.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Distribution package intelligence
12 package statesRelease-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.
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 release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Alpine v3.23v3.23 · community | firefox-esr | Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected. | 60.6.1-r0 | Alpine Security Database ↗Source updated 22 Oct 2026 |
| Alpine v3.22v3.22 · community | firefox-esr | Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected. | 60.6.1-r0 | Alpine Security Database ↗Source updated 22 Oct 2026 |
| Alpine v3.21v3.21 · community | firefox-esr | Vendor fix publishedAlpine records a security fix at this version. An absent entry does not mean the package is unaffected. | 60.6.1-r0 | Alpine Security Database ↗Source updated 22 Oct 2026 |
| Debian trixietrixie · source | firefox-esr | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 23 Oct 2026 |
| Debian trixietrixie · source | thunderbird | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 23 Oct 2026 |
| Debian bookwormbookworm · source | firefox-esr | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 23 Oct 2026 |
| Debian bookwormbookworm · source | thunderbird | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 23 Oct 2026 |
| Debian forkyforky · source | firefox-esr | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 23 Oct 2026 |
| Debian forkyforky · source | thunderbird | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 23 Oct 2026 |
| Debian sidsid · source | firefox | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 23 Oct 2026 |
| Debian sidsid · source | firefox-esr | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 23 Oct 2026 |
| Debian sidsid · source | thunderbird | Not affectedDebian marks this release not affected (fixed-version marker 0). | Not published in this feed | Debian Security Tracker ↗Source updated 23 Oct 2026 |
Critical technical impact with a remotely reachable, unauthenticated path; no CISA KEV confirmation is currently recorded.
Fix not verified01
What, why and how
A vulnerability was discovered where specific command line arguments are not properly discarded during Firefox invocation as a shell handler for URLs. This could be used to retrieve and execute files whose location is supplied through these command line arguments if Firefox is configured as the default URI handler for a given URI scheme in third party applications and these applications insufficiently sanitize URL data. *Note: This issue only affects Windows operating systems. Other operating systems are unaffected.*. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.
What
A vulnerability was discovered where specific command line arguments are not properly discarded during Firefox invocation as a shell handler for URLs. This could be used to retrieve and execute files whose location is supplied through these command line arguments if Firefox is configured as the default URI handler for a given URI scheme in third party applications and these applications insufficiently sanitize URL data. *Note: This issue only affects Windows operating systems. Other operating systems are unaffected.*. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.
Why
The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
What
A vulnerability was discovered where specific command line arguments are not properly discarded during Firefox invocation as a shell handler for URLs. This could be used to retrieve and execute files whose location is supplied through these command line arguments if Firefox is configured as the default URI handler for a given URI scheme in third party applications and these applications insufficiently sanitize URL data. *Note: This issue only affects Windows operating systems. Other operating systems are unaffected.*. This vulnerability affects Thunderbird < 60.6, Firefox ESR < 60.6, and Firefox < 66.
Why
The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.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 → Improper Neutralization of Argument Delimiters in a Command ('Argument Injection') → cause the confidentiality, integrity or availability impact described by the vendor
- 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-88 ↗
CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection'). The product constructs a string for a command to be executed by a separate component in another control sphere, but it does not properly delimit the intended arguments, options, or switches within that command string.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCommon Vulnerability Scoring System 3.0: 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.
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
- Thunderbird: unspecified < 60.6
- Firefox ESR: unspecified < 60.6
- Firefox: unspecified < 66
- 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 26 Apr 2019 · Last source change 4 Aug 2024, 22:01 UTC · CWE-88 · Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-09-01
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2019-19156
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceNIST NVD
NVD statusNVD modified after enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- ENISA EUVD mappingEUVD-2019-19156 was added to the official ENISA EUVD mapping for this CVE.ENISA EUVD ↗
- Before
- not recorded
- After
- {"euvdId":"EUVD-2019-19156"}
- Vendor guidanceAuthoritative vendor guidance changed: added vendor advisory: bugzilla.mozilla.org/show_bug.cgi?id=1530103; added vendor advisory: mozilla.org/mfsa2019-07; 2 further additions.mozilla.org ↗
- Before
- no authoritative guidance recorded
- After
- vendor advisory: bugzilla.mozilla.org/show_bug.cgi?id=1530103 · vendor advisory: mozilla.org/mfsa2019-07 · vendor advisory: mozilla.org/mfsa2019-08 · 1 more references
- SeveritySeverity changed from Unknown to Critical.NIST NVD ↗
- Before
- Unknown
- After
- Critical
- CVSS scoreCVSS score changed from not recorded to 9.8 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H).NIST NVD ↗
- Before
- not recorded
- After
- 9.8 (CVSS 3.0 · NIST NVD · CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
- Catalogue recordCVE added to the BlackTree catalogue.CNA ↗
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.