Security readout for executives and security teams
Plain-English summary
Microsoft Edge has a flaw where two parts of the browser can access shared data at the same time in the wrong order, letting a signed-in user on the same device view small pieces of information they should not see. It is a local issue, not a remote attack, and Microsoft has published guidance through its Security Update Guide.
Executive priority
Moderate but not urgent. Schedule within the normal monthly browser patch cycle. Elevate priority for shared workstations, kiosks, and VDI where multiple users share a host, since the flaw requires local authorized access.
Technical view
CVE-2026-55945 is a race condition (CWE-362) in Chromium-based Microsoft Edge caused by concurrent execution on a shared resource without proper synchronization. CVSS 3.1 is 4.2 (AV:L/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N) with exploit code unproven and an official fix available. An authorized local attacker who wins the race can disclose limited information across a security boundary.
Likely exposure
Any endpoint running an unpatched Chromium-based Microsoft Edge where a low-privileged local user can execute code or run browser content. Remote exposure is not indicated by the sources. Multi-user workstations, shared kiosks, and VDI hosts represent the most realistic exposure surface.
Exploitation context
Not listed in CISA KEV. Microsoft's advisory characterizes exploit code maturity as unproven and the attack complexity as high, meaning the attacker must reliably win a timing window. No public reports of in-the-wild exploitation are cited in the source bundle.
Researcher notes
CWE-362 race conditions in browser code paths typically involve shared caches, IPC handlers, or renderer/browser process boundaries. CVSS scope change with C:L/I:L suggests limited cross-boundary data leakage rather than full memory disclosure. Attack complexity High reflects timing sensitivity. Microsoft has not published detailed root cause or affected component; the advisory version string "1.0.0.0" in the CVE record is a placeholder — use MSRC for authoritative fixed builds.
Mitigation direction
- Apply the Microsoft Edge Stable channel update referenced in the MSRC advisory for CVE-2026-55945.
- Enable automatic Edge updates via Microsoft Edge Update policies on managed endpoints.
- Restrict local logon rights on shared and multi-user systems to reduce authorized-attacker exposure.
- Prioritize patching on VDI, kiosk, and shared-workstation fleets where local users co-reside.
- Consult Microsoft vendor guidance for any additional configuration workarounds if patching is delayed.
Validation and detection
- Inventory Edge versions across endpoints and compare against the fixed build listed in the MSRC advisory.
- Confirm Microsoft Edge Update service is running and policies are not blocking updates.
- Verify patch deployment through endpoint management reporting (Intune, SCCM, or equivalent).
- Spot-check edge://settings/help on representative hosts to confirm the patched version is active.
- Review MSRC advisory periodically for updated fixed-version guidance.
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-362: 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-2026-55945 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
- Medium
- CVSS
- 4.2 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C
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:L/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C1.12.7microsoftVulnerability scoring details
Base CVSS 3.1 score
4.2MediumVector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:N/E:U/RL:O/RC:C
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
- Microsoft Edge (Chromium-based) Information Disclosure VulnerabilityCVE reference, microsoft · vendor-advisory, patch
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.
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.