CVE-2026-82754 json
ash_authentication_oauth2_server aliases every protocol endpoint under /.well-known, bypassing path-scoped controls
published 2mo ago modified 2mo ago also EEF-CVE-2026-82754 , EUVD-2026-72536 , GHSA-wwxg-h779-3wf4
- cvss
- 6.3
- version 4.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 53%
- public exploits
- 0
- none known
Summary
Improper Protection of Alternate Path vulnerability in ash-project ash_authentication_oauth2_server exposes the state-changing OAuth endpoints under an unintended URL prefix, bypassing controls scoped to the canonical prefix.
oauth2_server_protocol_routes/1 in AshAuthentication.Phoenix.Oauth2Server.Router forwards the same ProtocolRouter at both the /oauth prefix and the /.well-known prefix. Phoenix forward strips the matched prefix before dispatch, so the full route table answers under both mounts, and POST /register, POST /token, and POST /revoke are reachable as /.well-known/register, /.well-known/token, and /.well-known/revoke. Edge controls such as WAF rules, rate limits, or authentication exemptions written against the /oauth paths, or that allow-list /.well-known as unauthenticated, do not apply to the alias.
This issue affects ash_authentication_oauth2_server: from 0.1.0 before 0.3.1.
Patch / fix
- hex ash_authentication_oauth2_server 0.3.1
- ash-project ash_authentication_oauth2_server 0.3.1
Is CVE-2026-82754 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- partial
- Assessed
- 2mo ago
Exploit prediction
0.69% chance of exploitation in the next 30 days, higher than 53% of all scored CVEs (FIRST EPSS, 2026-11-11).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 6.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N |
| CNA | 4.0 | 6.3 | CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/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 |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| hex | ash_authentication_oauth2_server | >=0.1.0, <0.3.1 |
0.3.1 |
Affected products
- ash-project ash_authentication_oauth2_server
Classification
- Weakness
-
- CWE-424 Improper Protection of Alternate Path
References
-
github.com
/ash-project/ash_authentication_oauth2_server/commit/a72972d7ed3eb74c05dfa0653a258ef14454459a
patch
-
github.com
/ash-project/ash_authentication_oauth2_server/security/advisories/GHSA-wwxg-h779-3wf4
vendor-advisory, related, advisory
-
cna.erlef.org
/cves/CVE-2026-82754.html
related, web
-
osv.dev
/vulnerability/EEF-CVE-2026-82754
related
-
hex.pm
/packages/ash_authentication_oauth2_server
package
Sources
- CVE List CVE-2026-82754
- NVD CVE-2026-82754
- OSV EEF-CVE-2026-82754
- Maintainer advisory GHSA-wwxg-h779-3wf4
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
The maintainers of ash-project/ash_authentication_oauth2_server published their own advisory on GitHub. Reviewed sources take precedence over it.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.