CVE-2026-126081

Action Pack: Possible Strong Parameters Bypass in Parameters#each_key

Products / packages rails · actionpack

Published 10/11/2026, 21:06:31 UTC

Severity and exploitation

Not in CISA KEVSource: HIGH

KEV coverage does not rule out exploitation.

KEV checked 14/11/2026, 23:35:33 UTC

OSV · CVSS:3.0 · 7.5

Assessment vector

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

GitHub_M · CVSS:3.1 · 7.5

Assessment vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

The headline uses the highest imported catalog score. Assessments can differ by source and CVSS version.

Severity

high7.5

CVSS measures technical severity, not the likelihood of an attack.

Known exploitation

Not listed in the checked CISA KEV catalog

Absence from CISA KEV does not rule out attacks.

Public exploit

Not established by this record

Missing evidence does not mean no public exploit exists.

Remediation

Package fixes recorded

Fix versions are recorded for 1 of 1 mapped packages. Check each release branch and any separate product guidance.

What this means

ActionController::Parameterseach_key delegates to the internal ActiveSupport::HashWithIndifferentAccess that holds the request parameters, so when called with a block it returns that hash instead of the Parameters instance. The hash does not respond to permitted?, so Active Model mass assignment (new, assign_attributes, update) accepts it without raising ActiveModel::ForbiddenAttributesError. An application that passes the return value of each_key to mass assignment could allow a remote, unauthenticated attacker to set attributes that the application does not permit, such as an…

Source excerpt · OSV

Attack conditions

No attack-condition excerpt has been identified here. Review the full source description and references for authentication, network access, and configuration requirements.

Review supporting sources →

Affected versions

Check the exact model, release, and any platform requirements against your installation.

rails · GitHub_M

rails

2 ranges

GitHub_M version evidence

Check a product version

Compare with this publisher’s ranges. This does not inspect your installation.

affected

>= 8.1, < 8.1.4.1

< 8.0.5.2

Other versions: unknown

Packages

Compare each installed version with the publisher’s affected ranges. Where a fix is recorded, choose the appropriate release branch and test compatibility before upgrading.

actionpack RubyGems

Affected range	Recorded fix
From 8.1.0.beta1 before 8.1.4.1Ecosystem versions	8.1.4.1
Earlier releases before 8.0.5.2Ecosystem versions	8.0.5.2

Version evidence: OSV · GHSA-wm3x-v3qw-4jh3

View original version evidence (520 explicit versions)

What to do

Compare your installed product and version with the affected versions above. A matching product name alone does not confirm exposure.

Use the recorded fix for your release branch. Review the publisher’s instructions and test compatibility before upgrading.

cve.new guidance unless attributed to a publisher. This page does not inspect your installation.

Public exploit evidence

No public exploit reference is identified in the imported evidence. This is not a claim that no exploit exists.

Original source description

Read the full publisher description

Impact

ActionController::Parameters#each_key delegates to the internal ActiveSupport::HashWithIndifferentAccess that holds the request parameters, so when called with a block it returns that hash instead of the Parameters instance. The hash does not respond to permitted?, so Active Model mass assignment (new, assign_attributes, update) accepts it without raising ActiveModel::ForbiddenAttributesError. An application that passes the return value of each_key to mass assignment could allow a remote, unauthenticated attacker to set attributes that the application does not permit, such as an authorization flag.

This is an incomplete fix of CVE-2020-8164, which made each, each_pair and each_value return the Parameters instance but left each_key delegated.

Details

The fixed releases define Parameters#each_key to yield each key and return the Parameters instance when given a block, as each, each_pair and each_value do, and to return an Enumerator without one. Code that used the return value of each_key as a hash now receives the Parameters instance, which mass assignment rejects unless it is permitted.

Affected applications

An application is affected if it passes the return value of ActionController::Parameters#each_key, called with a block, to mass assignment. Rails itself makes no such call.

Workarounds

Do not use the return value of each_key. Call it for its block only, and pass the permitted Parameters instance to mass assignment.

Releases

The fixed releases are available at the normal locations.

Patches for those who cannot upgrade at once:

Versions affected

actionpack < 8.0.5.2
actionpack >= 8.1, < 8.1.4.1

Credit

This issue was responsibly reported by HackerOne researcher smlee.

References

8 sources

rails/rails · security/advisories/GHSA-wm3x-v3qw-4jh3

Security advisoryGitHub_M

nvd.nist.gov/vuln/detail/CVE-2026-126081

Security advisory

rails/rails · commit 2fc8838

PatchGitHub_M

rails/rails · commit 8ba746e

PatchGitHub_M

rails/rails · repository

Source reference

rails/rails · releases/tag/v8.0.5.2

Release notesGitHub_M

View 2 more references

rails/rails · releases/tag/v8.1.4.1

Release notesGitHub_M

rubysec/ruby-advisory-db · GHSA-wm3x-v3qw-4jh3.yml

Source reference

Inside the record

Evidence available

Package identity

Version evidence

Remediation guidance · not supplied

Weakness classification

Additional publishers

Describes the evidence in this view, not whether the product is safe.

Original records

CVE-2026-126081

View the latest unmodified CVE JSON from the official source. It may be newer than this imported page.

cve.new JSON →

Underlying weaknesses

The source’s classification of what caused the vulnerability.

CWE-915 ↗

CWE-915: Improperly Controlled Modification of Dynamically-Determined Object Attributes

GitHub_M

Contributing organizations · 2

GitHub_M

Assigning organization

2026-11-10

CISA-ADP

Additional data publisher

2026-11-14

Timeline

All times UTC

10 Nov 2026, 21:06
Advisory published
Publication date supplied by the source.
14 Nov 2026, 03:08
Source updated
Latest modification date supplied by the source.
14 Nov 2026, 03:55
Last imported by cve.new
Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes

CVE · CVE-2026-1260812026-11-14

Observed 2026-11-14T03:55:50.839Z · upstream updated 2026-11-14T03:08:30.911Z

Prioritization updated

before

[]

after

[
  {
    "source": "CISA-ADP",
    "type": "SSVC",
    "role": "CISA Coordinator",
    "timestamp": "2026-11-14T03:08:20.462091Z",
    "decisions": [
      {
        "name": "Exploitation",
        "value": "none"
      },
      {
        "name": "Automatable",
        "value": "yes"
      },
      {
        "name": "Technical Impact",
        "value": "partial"
      }
    ]
  }
]

Large field values are marked as truncated previews. Original source snapshots remain retained.

Showing up to 50 most recent observed changes.

Reading the signals

Severity · CVSS: Technical impact and attack conditions. The headline is the highest imported catalog score; sources may disagree.
Observed exploitation · KEV: An absent or unavailable KEV listing does not establish that exploitation has not occurred.
Predicted exploitation · EPSS: 0.63% estimated probability in the next 30 days. 2026-11-12 · FIRST EPSS.

CISA-ADP · SSVC

CISA Coordinator · 2026-11-14

Exploitation: none
Automatable: yes
Technical Impact: partial

SSVC describes the publisher’s decision context. Your organization’s exposure and priorities may differ.

Record identifiers

Aliases: GHSA-wm3x-v3qw-4jh3

Source evidence

Request a correction or dispute

Start with the assigning organization for this record. Include the CVE ID, the disputed information, and supporting evidence. A dispute does not itself reject a record.

Find the responsible CNA →Official dispute and escalation process ↗

OSV GHSA-wm3x-v3qw-4jh3 CVE CVE-2026-126081

Enrichment coverage

NVDAvailable

Checked 13/11/2026, 00:10:33 UTC

GHSAAvailable

Checked 13/11/2026, 00:10:33 UTC

EUVDAvailable

Checked 13/11/2026, 00:10:34 UTC

EPSSAvailable

Checked 13/11/2026, 00:10:34 UTC

Additional source evidence

NVD · CVE-2026-126081

CVSS 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Checked 13/11/2026, 00:10:33 UTC

GitHub Advisory Database · GHSA-wm3x-v3qw-4jh3

CVSS 7.5 CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Checked 13/11/2026, 00:10:33 UTC

FIRST EPSS · CVE-2026-126081

EPSS 0.63% probability of exploitation in the next 30 days. Percentile: 50.49% · 2026-11-12

Checked 13/11/2026, 00:10:34 UTC

ENISA EUVD · EUVD-2026-122932

CVSS 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Checked 13/11/2026, 00:10:34 UTC

Sponsored by MoxsoBuild security habits with adaptive training and phishing simulations.View as JSON

Investigate in your agent.

Action Pack: Possible Strong Parameters Bypass in Parameters#each_key

Severity and exploitation

What this means

Attack conditions

Affected versions

rails

affected

unaffected

unknown

Packages

What to do

Public exploit evidence

Original source description

Impact

Details

Affected applications

Workarounds

Releases

Versions affected

Credit

References

Inside the record

Evidence available

Original records

Underlying weaknesses

Timeline

Advisory published

Source updated

Last imported by cve.new

What changed