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VulnerabilityPublished

CVE-2026-91039: team-alembic ash_authentication · Authentication Bypass by Spoofing

Affects team-alembic ash_authenticationSource CVE Database V5

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Not known to be exploited · CVSS 9.1 Critical : upgrade to 5.0.0-rc.14 as a priority.

Data as of 1 Nov 2026, 11:03 UTC

CVSS 4.0 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.6% chance of exploitation in 30 days – higher than 51% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 5.0.0-rc.14, 73ad16e452670bbf843550a13361bd41e72ad964
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 17 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 1 Nov 2026.

What to do

Upgrade ash_authentication to 5.0.0-rc.14; ash_authentication to 73ad16e452670bbf843550a13361bd41e72ad964.

Affected software

ProductAffectedFixed in
team-alembicash_authenticationAffected
  • >=5.0.0-rc.10 <5.0.0-rc.14
Fixed in
  • 5.0.0-rc.14
team-alembicash_authenticationAffected
  • ≥ 64530644f9b37ebb76ca14aeb83a77597a0034b7, < 73ad16e452670bbf843550a13361bd41e72ad964
Fixed in
  • 73ad16e452670bbf843550a13361bd41e72ad964
Hexash_authenticationpkg:hex/ash_authenticationOther threatsAffected
  • >=5.0.0-rc.10 <5.0.0-rc.14
Fixed in
  • 5.0.0-rc.14

CPE configurations (1)

  • cpe:2.3:a:team-alembic:ash_authentication:*:*:*:*:*:*:*:*

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, avoid using affected versions (>=5.0.0-rc.10 <5.0.0-rc.14) in production environments or implement additional identity verification controls to mitigate the risk.

Description

Authentication Bypass by Spoofing vulnerability in team-alembic ash_authentication allows an attacker who operates one identity-provider connection of a dynamic_oidc strategy to be signed in as a local user established through a different connection. The strategy is meant to keep each connection in its own identity namespace by writing every UserIdentity row's strategy field as "<name>/<connection_id>", but that namespacing never takes effect. __connection_id__ is populated only on the ephemeral runtime struct built per request in dynamic_oidc/plug.ex, and DynamicOidc.IdentityChange.change/3 re-fetches the strategy from the compile-time DSL through Info.strategy_for_action, yielding the persisted struct whose __connection_id__ is its defstruct default of nil. OAuth2.identity_strategy_name/1 therefore falls back to the bare strategy name for both the identity write and the reads in oauth2/user_resolver.ex and oauth2/sign_in_preparation.ex. Since the identity resource's unique key is (uid, strategy), one row exists per sub across every connection, and the identity-match branch runs before any email check. Neither strategy handles iss, so nothing else distinguishes the issuers: OpenID Connect Core section 5.7 makes sub unique only within an issuer, so two connections numbering subjects independently share one subject space. This issue affects ash_authentication: from 5.0.0-rc.10 before 5.0.0-rc.14.

References

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