CVE-2026-126067: Ruby on Rails

Summary

Action Pack is a framework for handling and responding to web requests. Prior to 8.1.4.1 and 8.0.5.2, Action Pack session stores other than ActionDispatch::Session::CookieStore (CacheStore, MemCacheStore, and third-party stores built on AbstractStore, AbstractSecureStore or the session mixins) write the session cookie without a SameSite attribute, regardless of config.action_dispatch.cookies_same_site_protection, which defaults to :lax. Only CookieStore applies the configured policy. In browsers that do not treat a cookie without the attribute as SameSite=Lax, a cross-site request could carry the session cookie, possibly leading to cross-site request forgery against actions that do not verify an authenticity token, such as those of API-only applications. Applications are affected when they use a session store other than CookieStore and do not pass same_site: to config.session_store. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.

cve.now Index

27Pcve.now Index 27 of 100 · methodology v3 · provisional

Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
Exposure7/25Reachable over the network without a login · Unknown: No advisory context yet
Reach17/20Affects Ruby on Rails (a widely deployed server, runtime, framework or database)
Severity3.1/10CVSS 3.1
No patch0/5No signal

What would change the score

Would score about 82 if added to CISA KEV
Would score about 77 if CISA's SSVC rates exploitation active
Would score about 42 if advisories confirm default setups are exposed

How the score works · Rankings

What to do

Upgrade to a fixed version: 8.1.4.1, 8.0.5.2.

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-2026-126067 (Action Pack: Missing SameSite attribute on session cookies from Action Pack session stores), 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-2026-126067 (entry last updated 2026-11-10):
Affected:
- rails rails: from 8.1, fixed in 8.1.4.1; fixed in 8.0.5.2
- RubyGems package actionpack: from 8.1.0.beta1, fixed in 8.1.4.1
- RubyGems package actionpack: fixed in 8.0.5.2
Fixed versions: 8.1.4.1, 8.0.5.2.
Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory.
CISA KEV: CVE-2026-126067 is not listed as of cve.now's last read.
This KEV status is for CVE-2026-126067 only. If you also check another CVE, look up its own KEV status; never assume it from this one.

How to check:
- Packages (RubyGems): find every lockfile in each project and run check_stack from the cve.now MCP server on each one. Compare the resolved versions, not the ranges a manifest declares, with the affected versions above. Include transitive dependencies.
- 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/rails/rails/security/advisories/GHSA-gmj8-hvj3-49mw
- https://github.com/rails/rails/commit/2d9f502df941e31ce9bad0e846564f49396bed46
- https://github.com/rails/rails/commit/f2392996be723708271a8d30bfcf0edc221e53ef
- https://github.com/rails/rails/releases/tag/v8.0.5.2
- https://github.com/rails/rails/releases/tag/v8.1.4.1
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.

Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action.

Entry: https://cve.now/CVE-2026-126067
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-2026-126067.

Timeline

Nov 10, 2026, 8:29 PM UTCCVE published
Nov 10, 2026, 9:26 PM UTCFirst seen by cve.now

Affected versions

rails rails
From 8.1 · fixed in 8.1.4.1; fixed in 8.0.5.2
actionpackRubyGems
From 8.1.0.beta1 · fixed in 8.1.4.1
actionpackRubyGems
fixed in 8.0.5.2

Evidence 7

Vendor advisory · 1

Establishes: Affected and fixed versions.

Advisory
GitHub · rails/rails · Advisory GHSA-gmj8-hvj3-49mw

CVE record · 2

Establishes: The identifier and description.

Record
CVE List · CVE-2026-126067
Record
NVD · CVE-2026-126067

Corrections

None so far.

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

Questions about CVE-2026-126067

Is CVE-2026-126067 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

Which versions are affected by CVE-2026-126067?

rails: from 8.1 before 8.1.4.1; before 8.0.5.2. actionpack (RubyGems): from 8.1.0.beta1 before 8.1.4.1. actionpack (RubyGems): before 8.0.5.2.Source: cve.now feed data

How do I fix CVE-2026-126067?

Upgrade to a fixed version: 8.1.4.1, 8.0.5.2.Source: cve.now feed data

Action Pack: Missing SameSite attribute on session cookies from Action Pack session stores