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Full vulnerability report · 2025
CVE-2025-1933High confidence

JIT corruption of WASM i32 return values on 64-bit CPUs

Mozilla · Firefox

7.6HighCVSS 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-2025-7438

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

On 64-bit CPUs, when the JIT compiles WASM i32 return values they can pick up bits from left over memory. This can potentially cause them to be treated as a different type. This vulnerability was fixed in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.

What

On 64-bit CPUs, when the JIT compiles WASM i32 return values they can pick up bits from left over memory. This can potentially cause them to be treated as a different type. This vulnerability was fixed in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through a network path may attempt exploitation without authentication after a user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

On 64-bit CPUs, when the JIT compiles WASM i32 return values they can pick up bits from left over memory. This can potentially cause them to be treated as a different type. This vulnerability was fixed in Firefox 136, Firefox ESR 115.21, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.

Why

The current structured CVE record identifies a security weakness, but the root cause requires confirmation in the linked vendor material.

How

An attacker operating through a network path may attempt exploitation without authentication after a 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 → vulnerable operation → cause the confidentiality, integrity or availability impact described by the vendor
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.
CWE not yet assigned
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:L/I:L/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.CLowConfidentiality impact: A successful attack can cause a limited loss.ILowIntegrity impact: A successful attack can cause a limited 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.
NetworkUnauthenticated
A

Official authority intelligence

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

BSI · German · WID-SEC-W-2025-0482Mozilla Firefox, Mozilla Firefox ESR und Mozilla Thunderbird: Mehrere Schwachstellen

Ein entfernter, anonymer Angreifer kann mehrere Schwachstellen in Mozilla Firefox, Mozilla Firefox ESR und Mozilla Thunderbird ausnutzen, um Spoofing-Angriffe durchzuführen, Sicherheitsmaßnahmen zu umgehen, erhöhte Privilegien zu erlangen, einen Denial-of-Service-Zustand herbeizuführen, vertrauliche Informationen offenzulegen, Daten zu manipulieren, beliebigen Code auszuführen oder nicht spezifizierte Auswirkungen zu verursachen.

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

.cve.org/CVERecord?id=CVE-2025-1918 Référence CVE CVE-2025-1919 https://www.cve.org/CVERecord?id=CVE-2025-1919 Référence CVE CVE-2025-1920 https://www.cve.org/CVERecord?id=CVE-2025-1920 Référence CVE CVE-2025-1921 https://www.cve.org/CVERecord?id=CVE-2025-1921 Référence CVE CVE-2025-1922 https://www.cve.org/CVERecord?id=CVE-2025-1922 Référence CVE CVE-2025-1923 https://www.cve.org/CVERecord?id=CVE-2025-1923 Référence CVE CVE-2025-1930 https://www.cve.org/CVERecord?id=CVE-2025-1930 Référence CVE CVE-2025-1931 https://www.cve.org/CVERecord?id=CVE-2025-1931 Référence CVE CVE-2025-1932 https://www.cve.org/CVERecord?id=CVE-2025-1932 Référence CVE CVE-2025-1933 https://www.cve.org/CVERecord?id=CVE-2025-1933 Référence CVE CVE-2025-1934 https://www.cve.org/CVERecord?id=CVE-2025-1934 Référence CVE CVE-2025-1935 https://www.cve.org/CVERecord?id=CVE-2025-1935 Référence CVE CVE-2025-1936 https://www.cve.org/CVERecord?id=CVE-2025-1936 Référence CVE CVE-2025-1937 https://www.cve.org/CVERecord?id=CVE-2025-1937 Référence CVE CVE-2025-1938 https://www.cve.org/CVERecord?id=CVE-2025-1938 Référence CVE CVE-2025-1939 https://www.cve.org/CVERecord?id=CVE-2025-1939 Référence CVE CVE-2025-1940 https://www.cve.org/CVERecord?id=CVE-2025-1940 Référence CVE CVE-2025-1941 https://www.cve.org/CVERecord?id=CVE-2025-1941 Ré

Official advisory
CERT-FR · French · CERTFR-2025-AVI-0176Multiples 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
115.21 ≤ 115.*; 128.8 ≤ 128.*; 136 ≤ *
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 4 Mar 2025 · Last source change 4 Jun 2026, 14:47 UTC · CWE not yet assigned

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-2025-7438
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceUnavailable
NVD statusNVD modified after enrichment

Missing structured fields: affected versions, CWE classification. 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-2025-1933 · cve.blacktree.nl