CVE-2026-120999: nerves_hub_web auth bypass in sign-in flow

Summary

Improper authentication in NervesHub's web application lets a remote attacker who registers someone else's email address share that person's account once the owner signs in with Google or follows an email confirmation link. The attacker needs no login of their own, and the victim's sign-in or confirmation click is what gives the attacker access.

Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.

Read the original description

Improper Authentication vulnerability in Google sign-in and email confirmation in nerves-hub nerves_hub_web allows an attacker who registers another person's email address to share that person's account once they sign in. NervesHub.Accounts.update_or_create_user_from_ueberauth/1 signs a Google user in to any account carrying the same email that is not yet linked to a Google account, links it and marks the email confirmed, without the account's owner ever having proved they own the address. NervesHubWeb.SessionController.confirm/2 likewise signs in whoever follows a confirmation link. An attacker registers the address from the sign-up form, changes their own account's email to it, or registers it as an organization admin from an invite link, and keeps the password; when the address's owner signs in with Google or follows the confirmation link, they land in that account.

The Google path also creates accounts with registrations closed and never checks Google's email_verified claim, and the API's password sign-in in NervesHubWeb.API.UserController issues tokens to accounts whose email was never confirmed. The attacker gains only what the victim is granted afterwards, and nothing on accounts whose owners never use either path.

This issue affects nerves_hub: from 2.3.0 before 2.5.3.

cve.now Index

19Pcve.now Index 19 of 100 · methodology v3 · provisional

Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
Exposure12/25Specific setups only, reachable over the network without a login
Reach?/20Unknown. No tracked technology or package matched
Severity7.4/10CVSS 7.4
No patch0/5No signal

What would change the score

Would score about 69 if added to CISA KEV
Would score about 64 if CISA's SSVC rates exploitation active

How the score works · Rankings

What to do

Check whether your setup matches what the bug needs.
Google sign-in is turned on (GOOGLE_CLIENT_ID set) for the Google path Affected versions are 2.3.0 before 2.5.3
Upgrade to a fixed version: 2.5.3.
Workaround: Turn off Google sign-in by unsetting GOOGLE_CLIENT_ID until the upgrade; users who only sign in with Google cannot sign in while it is off.

Check your systems with an agent

Paste this into a coding or ops agent. It checks your systems read-only and reports a table per asset.

Check whether my systems are affected by CVE-2026-120999 (Improper authentication lets Google sign-in and confirmation links sign users in to accounts registered with their email address by…), using the cve.now data below.

Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only.

What cve.now has for CVE-2026-120999 (entry last updated 2026-11-10):
Affected:
- nerves-hub nerves_hub_web: from 2.3.0, fixed in 2.5.3
- nerves-hub nerves_hub_web: from 2.3.0, fixed in 2.5.3
- nerves-hub nerves_hub_web: version range not reported
Fixed versions: 2.5.3.
Conditions (all must be true for the bug to be hit):
- Google sign-in is turned on (GOOGLE_CLIENT_ID set) for the Google path (source: https://github.com/nerves-hub/nerves_hub_web/security/advisories/GHSA-r92p-gg92-gmwm)
- Affected versions are 2.3.0 before 2.5.3 (source: https://github.com/nerves-hub/nerves_hub_web/security/advisories/GHSA-r92p-gg92-gmwm)
Setup: the bug needs a feature or setting that is off by default or uncommon. Check whether each asset has it on.
Attacker needs: network access, no login, a user action.
Workaround: Turn off Google sign-in by unsetting GOOGLE_CLIENT_ID until the upgrade; users who only sign in with Google cannot sign in while it is off. (source: https://github.com/nerves-hub/nerves_hub_web/security/advisories/GHSA-r92p-gg92-gmwm)
CISA KEV: CVE-2026-120999 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-120999 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory.

Verify against the linked advisories before concluding, and cite the date you read each one:
- https://github.com/nerves-hub/nerves_hub_web/security/advisories/GHSA-r92p-gg92-gmwm
- https://github.com/nerves-hub/nerves_hub_web/commit/54dbf93c3bd323df08223a853c9afcf0b4dbf8e4
- https://cna.erlef.org/cves/CVE-2026-120999.html
- https://osv.dev/vulnerability/EEF-CVE-2026-120999
- https://github.com/nerves-hub/nerves_hub_web/commit/74982672ab914bd6f37c3bc0e24a06e3474fa030
Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing.

Entry: https://cve.now/CVE-2026-120999
For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example get_vulnerability with id CVE-2026-120999.

Timeline

Nov 10, 2026, 10:43 AM UTCCVE published
Nov 10, 2026, 10:51 AM UTCFirst seen by cve.now

Affected versions

nerves-hub/nerves-hub
From 2.3.0 · fixed in 2.5.3
nerves_hub
From 2.3.0 · fixed in 2.5.3
nerves-hub/nerves_hub_web
Version range not reported

Evidence 7

Vendor advisory · 1

Establishes: Affected and fixed versions.

Advisory
GitHub · nerves-hub/nerves_hub_web · Advisory GHSA-r92p-gg92-gmwm

CVE record · 2

Establishes: The identifier and description.

Record
CVE List · CVE-2026-120999
Record
NVD · CVE-2026-120999

Corrections

None so far.

Something wrong on this page? Report an error. Every fix is listed here.

Questions about CVE-2026-120999

Is CVE-2026-120999 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data

What does this mean?

An attacker who registers someone else's email address can get into that person's account after the victim signs in with Google or follows an email confirmation link. The attacker keeps the password they chose and can see and do whatever the victim can in every organization the victim joins, at the victim's role.Source: github.com, cna.erlef.org

Which versions are affected by CVE-2026-120999?

nerves-hub/nerves-hub: from 2.3.0 before 2.5.3. nerves_hub: from 2.3.0 before 2.5.3.Source: cve.now feed data

Am I affected, and how do I check?

Releases 2.3.0 through 2.5.2 of nerves_hub_web are affected, and only instances with Google sign-in turned on, meaning GOOGLE_CLIENT_ID is set. To check, look at the installed version and whether GOOGLE_CLIENT_ID is set in the environment.Source: github.com, cna.erlef.org

How do I fix CVE-2026-120999?

Upgrade nerves_hub_web to 2.5.3, which contains the fix. Until the upgrade is applied, the advisory's workaround is to unset GOOGLE_CLIENT_ID, which turns off Google sign-in.Source: github.com, cna.erlef.org

Improper authentication lets Google sign-in and confirmation links sign users in to accounts registered with their email address by…