Security readout for executives and security teams
Plain-English summary
CVE-2026-2781 is a high-severity integer overflow in Mozilla NSS libraries affecting Mozilla browser and mail products. Mozilla says it is fixed in Firefox 148, Firefox ESR 140.8, Firefox ESR 115.35, Thunderbird 148, and Thunderbird 140.8. Business urgency is high for endpoints using these products, but no provided source shows active exploitation.
Executive priority
Prioritize within the next normal emergency patch cycle for user endpoints, especially managed browsers and email clients. The combination of high CVSS impact and common desktop exposure justifies rapid remediation, even without confirmed active exploitation.
Technical view
The issue is CWE-190 integer overflow in the NSS Libraries component. The CVSS 3.1 score is 8.8 with network attack vector, low complexity, no privileges required, and user interaction required. Impact is rated high for confidentiality, integrity, and availability. Public sources do not provide safe operational detail on the vulnerable code path.
Likely exposure
Exposure is most likely on workstations or servers running Mozilla Firefox, Firefox ESR, or Thunderbird versions prior to the fixed releases named by Mozilla. Debian LTS environments may also need package-level review based on the Debian advisory reference.
Exploitation context
The CVSS vector indicates remote network reachability with required user interaction. CISA KEV status in the provided bundle is false, and no cited source states active exploitation. Treat this as a serious patching issue, not as confirmed in-the-wild exploitation.
Researcher notes
Available public metadata identifies component, CWE, CVSS, and fixed product releases, but not detailed root cause or exploit preconditions. Avoid assuming broader NSS consumer impact unless vendor or distribution advisories confirm it. Track Mozilla Bugzilla and advisories for additional disclosure.
Mitigation direction
- Update Firefox to Mozilla’s fixed release listed for the installed branch.
- Update Firefox ESR to the fixed ESR release for the installed branch.
- Update Thunderbird to Mozilla’s fixed release listed for the installed branch.
- For Debian LTS, follow the referenced Debian security advisory and package updates.
- If immediate updating is delayed, check Mozilla and OS vendor guidance for supported mitigations.
Validation and detection
- Inventory installed Firefox, Firefox ESR, Thunderbird, and NSS-related distribution packages.
- Compare installed versions against Mozilla’s fixed versions in the advisories.
- Confirm endpoint management reports successful update deployment.
- Review Debian LTS advisory applicability for Linux systems using vendor packages.
- Monitor Mozilla advisories and CVE records for later corrections or exploitation updates.
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-190: 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-2026-2781 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
- High
- CVSS
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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.
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:R/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://bugzilla.mozilla.org/show_bug.cgi?id=2009552CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-13/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-15/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-16/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-17/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-31/CVE reference
- https://lists.debian.org/debian-lts-announce/2026/03/msg00012.htmlCVE reference
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.
Integer Overflow or Wraparound
Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.