Security readout for executives and security teams
Plain-English summary
Mozilla reports a critical memory-handling flaw where certain uppercase conversion could place uninitialized memory into a resulting string. In business terms, sensitive data from process memory could be exposed through Firefox or Thunderbird behavior. The provided sources say the issue was fixed in Firefox 136 and Thunderbird 136.
Executive priority
Treat this as a near-term patching priority for browser and email fleets. The direct business risk is unintended memory disclosure from widely deployed user applications. No active exploitation is proven in the supplied sources, but the critical CVSS score and low attack complexity justify accelerated remediation tracking.
Technical view
CVE-2025-1942 is CWE-908: use of uninitialized resource. When String.toUpperCase() made a string longer, uninitialized memory could be incorporated into the output string. The CVSS 3.1 vector is 9.8 critical, with network attack vector, low complexity, no privileges, and no user interaction.
Likely exposure
Exposure centers on Mozilla Firefox and Thunderbird deployments that do not have the vendor fix identified in the sources. The bundle does not provide ESR, mobile, Linux distribution, or downstream package details, so vulnerability managers should confirm product-specific applicability with Mozilla and package vendor guidance.
Exploitation context
The provided bundle does not confirm active exploitation. CISA KEV status is false, and no cited source in the bundle states exploitation in the wild. Treat the issue as urgent because the CVSS score is 9.8 and the flaw can disclose uninitialized memory.
Researcher notes
The public description is concise and does not include exploit mechanics, affected code paths beyond String.toUpperCase(), or downstream package scope. Validation should focus on version evidence and Mozilla advisory mapping rather than attempting reproduction. Avoid assuming exploitation or affected products beyond Firefox and Thunderbird.
Mitigation direction
- Update Firefox to the vendor-fixed release or later.
- Update Thunderbird to the vendor-fixed release or later.
- Prioritize managed endpoints that process sensitive web or email content.
- Check Mozilla advisories for product-specific deployment guidance.
- Review OS package vendor notices for downstream build timing.
Validation and detection
- Inventory Firefox and Thunderbird versions across managed endpoints.
- Confirm installed builds include the fix referenced by Mozilla.
- Check vulnerability scanner findings against Mozilla advisory identifiers.
- Verify browser and mail client update policies are enforcing current releases.
- Document any unsupported or unmanaged systems needing manual remediation.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-908: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2025-1942 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.mozilla.org/show_bug.cgi?id=1947139CVE reference, mozilla
- https://www.mozilla.org/security/advisories/mfsa2025-14/CVE reference, mozilla
- https://www.mozilla.org/security/advisories/mfsa2025-17/CVE reference, mozilla
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Use of Uninitialized Resource
Use of Uninitialized Resource represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.