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Full vulnerability report · 2025
CVE-2025-6435High confidence

Save as in Devtools could download files without sanitizing the extension

Mozilla · Firefox

8.1HighCVSS 3.1
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

2 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.

Ubuntu releaseSource packageVendor stateFixed versionEvidence
Ubuntu 24.04 LTSnoble · standard archivemozjs102Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical record ↗Source updated 8 Sept 2026
Ubuntu 24.04 LTSnoble · standard archivemozjs115Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.Not published in this feedCanonical record ↗Source updated 8 Sept 2026
Optional official sources

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

Select the national-authority views to include. The exact source language is shown on each matched advisory. Your choice is remembered on this device and encoded in the shareable URL.

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-2025-19016

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 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

If a user saved a response from the Network tab in Devtools using the Save As context menu option, that file may not have been saved with the `.download` file extension. This could have led to the user inadvertently running a malicious executable. This vulnerability was fixed in Firefox 140 and Thunderbird 140.

What

If a user saved a response from the Network tab in Devtools using the Save As context menu option, that file may not have been saved with the `.download` file extension. This could have led to the user inadvertently running a malicious executable. This vulnerability was fixed in Firefox 140 and Thunderbird 140.

Why

The upload path does not sufficiently restrict the type, name, location or later execution of attacker-supplied files.

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

If a user saved a response from the Network tab in Devtools using the Save As context menu option, that file may not have been saved with the `.download` file extension. This could have led to the user inadvertently running a malicious executable. This vulnerability was fixed in Firefox 140 and Thunderbird 140.

Why

The upload path does not sufficiently restrict the type, name, location or later execution of attacker-supplied files.

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
?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.
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 → Unrestricted Upload of File with Dangerous Type → 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
High: exploitation depends on specific conditions
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-434

CWE-434: Unrestricted Upload of File with Dangerous Type. The product allows the upload or transfer of dangerous file types that are automatically processed within its environment.

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:H/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.ACHighAttack complexity: Successful exploitation depends on specific conditions outside the attacker's direct control.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.
NetworkUnauthenticatedCWE-434
A

Official authority intelligence

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

BSI · German · WID-SEC-W-2025-1395Mozilla Firefox: Mehrere Schwachstellen

Ein Angreifer kann mehrere Schwachstellen in Mozilla Firefox und Mozilla Firefox ESR ausnutzen, um beliebigen Code auszuführen, einen Denial-of-Service-Angriff auszulösen, Sicherheitsmaßnahmen zu umgehen oder einen Cross-Site-Scripting-Angriff zu starten.

Official advisory
BSI · German · WID-SEC-W-2025-1850Xerox FreeFlow Print Server: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff

Ein Angreifer kann mehrere Schwachstellen in Xerox FreeFlow Print Server ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.

Official advisory
CERT-FR · French · CERTFR-2025-AVI-0756Multiples vulnérabilités dans les produits VMware

.cve.org/CVERecord?id=CVE-2025-6424 Référence CVE CVE-2025-6425 https://www.cve.org/CVERecord?id=CVE-2025-6425 Référence CVE CVE-2025-6426 https://www.cve.org/CVERecord?id=CVE-2025-6426 Référence CVE CVE-2025-6427 https://www.cve.org/CVERecord?id=CVE-2025-6427 Référence CVE CVE-2025-6429 https://www.cve.org/CVERecord?id=CVE-2025-6429 Référence CVE CVE-2025-6430 https://www.cve.org/CVERecord?id=CVE-2025-6430 Référence CVE CVE-2025-6432 https://www.cve.org/CVERecord?id=CVE-2025-6432 Référence CVE CVE-2025-6433 https://www.cve.org/CVERecord?id=CVE-2025-6433 Référence CVE CVE-2025-6434 https://www.cve.org/CVERecord?id=CVE-2025-6434 Référence CVE CVE-2025-6435 https://www.cve.org/CVERecord?id=CVE-2025-6435 Référence CVE CVE-2025-6436 https://www.cve.org/CVERecord?id=CVE-2025-6436 Référence CVE CVE-2025-6554 https://www.cve.org/CVERecord?id=CVE-2025-6554 Référence CVE CVE-2025-6555 https://www.cve.org/CVERecord?id=CVE-2025-6555 Référence CVE CVE-2025-6556 https://www.cve.org/CVERecord?id=CVE-2025-6556 Référence CVE CVE-2025-6557 https://www.cve.org/CVERecord?id=CVE-2025-6557 Référence CVE CVE-2025-6558 https://www.cve.org/CVERecord?id=CVE-2025-6558 Référence CVE CVE-2025-6965 https://www.cve.org/CVERecord?id=CVE-2025-6965 Référence CVE CVE-2025-7339 https://www.cve.org/CVERecord?id=CVE-2025-7339 Ré

Official advisory
CERT-FR · French · CERTFR-2025-AVI-0555Multiples vulnérabilités dans Mozilla Thunderbird

De multiples vulnérabilités ont été découvertes dans Mozilla Thunderbird. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, un déni de service à distance et une atteinte à la confidentialité des données.

Official advisory
CERT-FR · French · CERTFR-2025-AVI-0536Multiples vulnérabilités dans les produits Mozilla

De multiples vulnérabilités ont été découvertes dans les produits Mozilla. Certaines d'entre elles permettent à un attaquant de provoquer une exécution de code arbitraire à distance, un déni de service à distance et une atteinte à la confidentialité des données.

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
See the vendor and CVE records for the affected range.
Fixed
140 ≤ *
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
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 24 Jun 2025 · Last source change 13 Apr 2026, 14:31 UTC · CWE-434 · Unrestricted Upload of File with Dangerous Type

CVE recordCVE.org · 5.2
CVSS sourceCISA ADP
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2025-19016
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCISA ADP
NVD statusNVD modified after enrichment

Missing structured fields: affected versions. Missing data is not evidence of low risk; review the primary advisory.

Material change intelligence

What changed after publication

View recent updates →

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
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-2025-6435 · cve.blacktree.nl