AshAdmin cookie reader matches names by substring, enabling actor/session shadowing from a sibling subdomain (CVE-2026-75757) | HOL Guard CVE

Unknown severity · Source severity not reportedCVE-2026-75757

AshAdmin cookie reader matches names by substring, enabling actor/session shadowing from a sibling subdomain

Answer in brief

CVE-2026-75757 records a Unknown severity vulnerability in AshAdmin cookie reader matches names by substring, enabling actor/session shadowing from a sibling subdomain. The current sources do not mark it as known exploited. The current feed maps ash-project/ash_admin (generic), ash-project/ash_admin (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Aug 31, 2026Updated Aug 31, 2026Source checked Aug 31, 2026First seen by HOL Aug 31, 2026Material review Aug 31, 2026

Upstream Advisory

Key facts

Risk: Unknown severitySource severity not reported
Exploitation: Not marked as known exploited
Affected software: 2 mapped packages or products
Fix availability: Available

Why this deserves its current priority

A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps ash-project/ash_admin (generic), ash-project/ash_admin (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
ash-project/ash_admingeneric	>=0.9.1 <1.3.1	1.3.1
ash-project/ash_admingeneric	>=77a43cc4fa04cb59c38fc434568a35a38ecb995a <e93a3408a85035e1f90275d02bc2470c96095e56	e93a3408a85035e1f90275d02bc2470c96095e56

Recommended response

Check inventory. Check lockfiles and deployed manifests for ash-project/ash_admin, ash-project/ash_admin.
Review the reported fix. Update ash-project/ash_admin to 1.3.1; ash-project/ash_admin to e93a3408a85035e1f90275d02bc2470c96095e56 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Aug 31, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Aug 31, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Aug 31, 2026

Sources and claim methodology

Upstream source description

Reliance on Cookies without Validation and Integrity Checking vulnerability in ash-project ash_admin lets an attacker who controls a sibling subdomain rebind an admin's session to a different actor, tenant, or authorization mode. AshAdmin's client JavaScript read its state cookies (tenant, actor_resource, actor_primary_key, actor_action, actor_domain, actor_authorizing, actor_paused) by matching the cookie name with an unanchored regular expression (new RegExp(name + "=([^;]+)")) against the whole document.cookie. Any cookie whose name merely ends with the requested name therefore matches, and whichever is serialized first wins. Because cookies are shared across a registrable domain, a compromised sibling subdomain can set a shadowing cookie (for example xactor_authorizing) with Domain=.example.com that flows unvalidated into the admin's LiveSocket connect params. The fix matches cookie names by exact equality. This issue affects ash_admin: from 0.9.1 before 1.3.1.

Quoted source text, attributed separately from HOL analysis.