Security readout for executives and security teams
Plain-English summary
CVE-2026-2789 is a high-severity memory safety flaw in Mozilla’s ImageLib graphics component. A user would need to interact with attacker-controlled content. Successful exploitation could affect confidentiality, integrity, and availability. Mozilla states the issue is fixed in current Firefox, Firefox ESR, and Thunderbird releases listed in its advisories.
Executive priority
Treat as a high-priority endpoint update. The issue has severe potential impact but requires user interaction, and the provided sources do not indicate known active exploitation. Patch promptly through normal emergency or accelerated browser-update processes.
Technical view
The flaw is a CWE-416 use-after-free in Graphics: ImageLib. CVSS 3.1 is 8.8: network-reachable, low complexity, no privileges required, user interaction required, with high confidentiality, integrity, and availability impact. Mozilla identifies fixes in Firefox 148, Firefox ESR 115.33/140.8, Thunderbird 148, and Thunderbird 140.8.
Likely exposure
Organizations using Mozilla Firefox, Firefox ESR, or Thunderbird should check whether endpoints are below the fixed versions named by Mozilla. Exposure is most relevant on desktops and managed workstations where users browse or open content that can invoke image parsing.
Exploitation context
The provided sources do not show CISA KEV listing or active exploitation. The CVSS vector indicates exploitation requires user interaction but no authentication. The affected component processes images, making untrusted web or message content a plausible exposure path, but the sources do not provide exploit details.
Researcher notes
Public details are limited to a use-after-free in ImageLib and Mozilla advisory references. Avoid assuming exploitability beyond the CVSS impacts. Bugzilla and MFSA pages should be checked for any access-controlled notes, affected-version clarifications, or follow-up advisories.
Mitigation direction
- Update Firefox to version 148 or the applicable fixed ESR release.
- Update Thunderbird to version 148 or 140.8 as applicable.
- Prioritize managed desktop fleets and systems handling untrusted web or message content.
- If versions differ by platform, confirm current Mozilla advisory guidance.
Validation and detection
- Inventory deployed Firefox, Firefox ESR, and Thunderbird versions.
- Confirm versions meet or exceed Mozilla’s fixed releases.
- Review patch management reports for failed or deferred browser and mail-client updates.
- Monitor Mozilla advisories for revisions or additional affected-version details.
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-416: 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-2026-2789 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=2015179CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-13/CVE reference
- https://www.mozilla.org/security/advisories/mfsa2026-14/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
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 After Free
Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.