NVD / CVE Program· CNA EEF

CVE-2026-80218: Sign-in token minted for one resource accepted by another in AshAuthentication

Noroxi assessment

Priority: Monitor (action score 30/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.63% (FIRST EPSS); higher than 50.7% of all records.
Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
Fixed version: team-alembic ash_authentication 2640e1872e1fef4e4606e601bf00102cff784c03, 4.15.0, 5.0.0-rc.14.

Low priority for now. Upgrade to team-alembic ash_authentication 2640e1872e1fef4e4606e601bf00102cff784c03, 4.15.0, 5.0.0-rc.14 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

Improper Authentication vulnerability in team-alembic AshAuthentication allows an attacker holding a sign-in token for one authenticated resource to be signed in as a user of a different resource. AshAuthentication.Strategy.Password.SignInWithTokenPreparation.extract_primary_keys_from_subject/2 parses the JWT sub claim (for example user?id=1) with URI.parse/1 and keeps only its query string, discarding the path segment that names the subject the token was issued for. Nothing else restores that binding: AshAuthentication.Jwt.verify/3 checks the signature, exp, nbf, jti and the library-version claims, the purpose check only requires sign_in, and the remaining comparison is over primary-key field names, which are identical across resources. The WebAuthn sign-in and remember-me preparations carry copies of the same helper and drop the path in the same way. The magic link sign-in path pins the subject name against the resource and is not affected. This issue affects ash_authentication: from 3.10.5 before 4.15.0 and from 5.0.0-rc.0 before 5.0.0-rc.14.

HighCVSS 7.6 · v4.0—No exploit Fix available

Auth bypass

Published: Sep 17, 2026
Updated: Sep 18, 2026
EPSS: 0.6% · 50th percentile
CWE: CWE-287

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.6 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.6%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · EEF: 7.6; NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

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Versions reported by the vendor

Affected version ranges reported by the assigning authority (EEF). Independent of NVD's CPE analysis and usually ahead of it.

team-alembic ash_authentication
- 3.10.5 and later · before 4.15.0affected · semver
- 5.0.0-rc.0 and later · before 5.0.0-rc.14affected · semver
- eca8cadea0f1595ed2c10a0c177b1da9aa9e5269 and lateraffected · gitfixed in 2640e1872e1fef4e4606e601bf00102cff784c03, 7baac243ca651eee127a84d672eee3fcff42e598

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Hex	ash_authentication	from 3.10.5 · before 4.15.0	4.15.0
Hex	ash_authentication	from 5.0.0-rc.0 · before 5.0.0-rc.14	5.0.0-rc.14

Same product

team-alembic: all records

Other highest-scoring records for the same primary product.

CVE-2026-76949Remember-me sign-in guard reads a session key that is never written in ash_authentication, allowing session replacement
36Monitor
CVE-2026-91039dynamic_oidc identities are not namespaced by connection in ash_authentication, allowing cross-connection account takeover
36Monitor
CVE-2026-88952OAuth2 sign-in attached to an existing account without an email comparison in AshAuthentication
36Monitor

Published before and after this one in the same product

← EarlierCVE-2026-66882Aug 25, 2026 · Reflected XSS in AshAuthentication confirmation and magic link interaction forms
8Monitor
← EarlierCVE-2026-78223Sep 17, 2026 · Token revocation record built from unverified JWT claims in AshAuthentication
27Monitor
Later →CVE-2026-81637Sep 17, 2026 · Replayable OAuth2 CSRF state retained after a failed callback in AshAuthentication
9Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
team-alembic ash_authentication	2640e1872e1fef4e4606e601bf00102cff784c03	Vendor (CNA)
team-alembic ash_authentication	4.15.0	Vendor (CNA)
team-alembic ash_authentication	5.0.0-rc.14	Vendor (CNA)
team-alembic ash_authentication	7baac243ca651eee127a84d672eee3fcff42e598	Vendor (CNA)
Hex:ash_authentication	4.15.0	Package registry (OSV)
Hex:ash_authentication	5.0.0-rc.14	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Peter Ullrichreporter
James Hartonremediation developer
Jonatan Männchen / EEFanalyst

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-889520 days apartOAuth2 sign-in attached to an existing account without an email comparison in AshAuthentication
36Monitor
CVE-2026-6563323 days apartPurpose-limited JWT accepted as full bearer authentication in AshAuthentication
30Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability

Attack vector: Network
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: X

Weakness class (CWE)

CWE-287 · Improper Authentication

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Root cause

Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.

The bug in code

The whole CWE-287 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1app.use("/admin", requireSession, adminRouter);
2

3// Route added later skips the middleware
4app.post("/admin-api/config", updateConfig);

Fixed

1const admin = express.Router();
2admin.use(requireSession, requireRole("admin"));
3

4admin.post("/config", updateConfig);
5app.use("/admin", admin);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Change log

Fix✗ → ✓Sep 28, 2026, 10:07 PM UTC

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References

cna.erlef.org/cves/CVE-2026-80218.html

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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