eef-cve-2026-81637
CVSS 2.3 osv_hex
Description
## Summary Insufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 `state` value to replay the callback and sign that victim into an attacker-controlled account. `AshAuthentication.Strategy.OAuth2.Plug.callback/2` clears the stored `session_params` through a rebinding step inside its `with` chain, `conn <- delete_session(conn, session_key)`. Elixir evaluates the `else` block in the scope enclosing the `with`, so every failure path (the provider returning `?error=access_denied`, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches `store_authentication_result/2` holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry. This issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.
Timeline
- Published
- unknown
- Last Modified
- unknown
CVSS Details
CVSS details not available.
Affected Products
No product information available.
Weaknesses (CWE)
References
- https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-3vcj-gxx8-3p44
- https://cna.erlef.org/cves/CVE-2026-81637.html
- https://github.com/team-alembic/ash_authentication/commit/c5f589058e04239263f50a1430eb17ea6d5dd1a2
- https://github.com/team-alembic/ash_authentication/commit/bd4352303bc9d72d007f6818775267585a4bcc2f
- https://github.com/team-alembic/ash_authentication/commit/d7f939cd02bd618bcaa304631846fa75ffc419d7
- https://hex.pm/packages/ash_authentication
Linked Vulnerabilities
No linked vulnerabilities found.
{
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"type": "GIT"
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],
"aliases": [
"CVE-2026-81637",
"GHSA-3vcj-gxx8-3p44"
],
"credits": [
{
"name": "Peter Ullrich",
"type": "REPORTER"
},
{
"name": "Jonatan Männchen / EEF",
"type": "ANALYST"
},
{
"name": "James Harton",
"type": "REMEDIATION_DEVELOPER"
}
],
"database_specific": {
"capec_ids": [
"CAPEC-60"
],
"cpe_ids": [
"cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*"
],
"cwe_ids": [
"CWE-613"
]
},
"details": "## Summary\n\nInsufficient Session Expiration vulnerability in team-alembic AshAuthentication allows an attacker who obtains a victim's OAuth2 `state` value to replay the callback and sign that victim into an attacker-controlled account.\n\n`AshAuthentication.Strategy.OAuth2.Plug.callback/2` clears the stored `session_params` through a rebinding step inside its `with` chain, `conn <- delete_session(conn, session_key)`. Elixir evaluates the `else` block in the scope enclosing the `with`, so every failure path (the provider returning `?error=access_denied`, an invalid code, a token-exchange error, or a registration or sign-in failure) reaches `store_authentication_result/2` holding the original connection and the session entry is never removed. The value the module's own comment describes as protection against a CSRF-related attack is therefore consumed only when authentication succeeds, and survives a cancelled or failed attempt until the next request phase or session expiry.\n\nThis issue affects ash_authentication: from 0.6.0 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.",
"id": "EEF-CVE-2026-81637",
"modified": "2026-09-17T13:26:03.786782668Z",
"published": "2026-09-17T13:09:06.571Z",
"references": [
{
"type": "ADVISORY",
"url": "https://github.com/team-alembic/ash_authentication/security/advisories/GHSA-3vcj-gxx8-3p44"
},
{
"type": "WEB",
"url": "https://cna.erlef.org/cves/CVE-2026-81637.html"
},
{
"type": "WEB",
"url": "https://github.com/team-alembic/ash_authentication/commit/c5f589058e04239263f50a1430eb17ea6d5dd1a2"
},
{
"type": "FIX",
"url": "https://github.com/team-alembic/ash_authentication/commit/bd4352303bc9d72d007f6818775267585a4bcc2f"
},
{
"type": "FIX",
"url": "https://github.com/team-alembic/ash_authentication/commit/d7f939cd02bd618bcaa304631846fa75ffc419d7"
},
{
"type": "PACKAGE",
"url": "https://hex.pm/packages/ash_authentication"
}
],
"schema_version": "1.9.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
}
],
"summary": "Replayable OAuth2 CSRF state retained after a failed callback in AshAuthentication"
}