CVE-2026-49757: team-alembic ash_authentication · Authentication Bypass by Spoofing
Affects team-alembic ash_authenticationSource CVE Database V5
Not known to be exploited · CVSS 9.2 Critical : upgrade to 5.0.0-rc.10 or 4.14.0 as a priority.
Data as of 29 Oct 2026, 19:04 UTC
- EPSS
- 0.6% chance of exploitation in 30 days – higher than 49% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.0.0-rc.10, 4.14.0
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 15 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
Public exploit code: GitHub proofs of concept
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade team-alembic ash_authentication to 5.0.0-rc.10 or 4.14.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| team-alembicash_authentication | Affected
| Fixed in
|
| team-alembicash_authentication | Affected
| Fixed in
|
| team-alembicash_authentication | Affected
| Fixed in– |
Hexash_authenticationpkg:hex/ash_authenticationOther threats | Affected
| Fixed in
|
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
The vendor has described a fix that changes user resolution to rely on the (strategy, sub) identity and only link accounts by email when the email_verified claim is trusted.
Description
CVE-2026-49757 is a critical authentication bypass vulnerability in team-alembic's ash_authentication library affecting versions from 0.1.0 before 4.14.0 and from 5.0.0-rc.0 before 5.0.0-rc.10. The flaw allows an attacker to take over local user accounts via OAuth2/OIDC sign-in by matching users based on email rather than the required unique OpenID Connect iss/sub claims. This enables an unauthenticated attacker who can register an OAuth provider account with a victim's email to impersonate that victim and gain their privileges. The issue arises because email addresses, including unverified or reused ones, were used as unique identifiers instead of the stable iss/sub combination. The fix involves resolving users by the (strategy, sub) identity and only linking by email if the email_verified claim is trusted.
References
- github.com/team-alembic/ash_authentication/security/advisories/GHSA-777c-2fxx-qr28 (opens in a new tab)
- cna.erlef.org/cves/CVE-2026-49757.html (opens in a new tab)
- osv.dev/vulnerability/EEF-CVE-2026-49757 (opens in a new tab)
- github.com/team-alembic/ash_authentication/commit/728b8d28c1b5f465fa1116ef044a815300fc733d (opens in a new tab)
- github.com/team-alembic/ash_authentication/commit/64530644f9b37ebb76ca14aeb83a77597a0034b7 (opens in a new tab)