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CVE-2026-126072

Action Pack: Possible DoS vulnerability in Action Controller Live streaming

Products / packages rails · actionpack

Published

Share

Severity and exploitation

Not in CISA KEVSource: MODERATE

KEV coverage does not rule out exploitation.

KEV checked 14/11/2026, 23:05:32 UTC
OSV · CVSS:3.1 · 5.9
Assessment vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub_M · CVSS:3.1 · 5.9
Assessment vectorCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
The headline uses the highest imported catalog score. Assessments can differ by source and CVSS version.

Severity

medium5.9

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::Live::Bufferclose pushes its end-of-stream marker onto the response's bounded queue while it holds the buffer's monitor. When the client has stopped reading and the queue is full, the push blocks, and Bufferabort, which runs when the client disconnects or a write times out, waits indefinitely for the same monitor. Each such response could permanently hold a web server thread and its ActionController::Live thread, possibly resulting in a DoS vulnerability through thread exhaustion.

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

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

affected

>= 8.1, < 8.1.4.1

< 8.0.5.2

unaffected

unknown

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 versions8.1.4.1
Earlier releases before 8.0.5.2Ecosystem versions8.0.5.2

Version evidence: OSV · GHSA-rwvh-fw6r-pwvp

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::Live::Buffer#close pushes its end-of-stream marker onto the response's bounded queue while it holds the buffer's monitor. When the client has stopped reading and the queue is full, the push blocks, and Buffer#abort, which runs when the client disconnects or a write times out, waits indefinitely for the same monitor. Each such response could permanently hold a web server thread and its ActionController::Live thread, possibly resulting in a DoS vulnerability through thread exhaustion.

Applications that stream responses with ActionController::Live, including send_stream, are affected. Applications that serve large files through Active Storage proxy mode are exposed to unauthenticated clients.

Releases

The fixed releases are available at the normal locations.

Patches for those who cannot upgrade at once:

Credit

This issue was found by the Anthropic OSS Scanner (ANT-2026-LDFW5N2T).

References

8 sources
rails/rails · security/advisories/GHSA-rwvh-fw6r-pwvp
Security advisoryGitHub_M
nvd.nist.gov/vuln/detail/CVE-2026-126072
Security advisory
rails/rails · commit 27ad18e
PatchGitHub_M
rails/rails · commit ccbfc09
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-rwvh-fw6r-pwvp.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-2026-126072

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-833 ↗

CWE-833: Deadlock

GitHub_M

Related →
Contributing organizations · 2
GitHub_M

Assigning organization

2026-11-10
CISA-ADP

Additional data publisher

2026-11-14

Timeline

All times UTC

  1. Advisory published

    Publication date supplied by the source.

  2. Source updated

    Latest modification date supplied by the source.

  3. Last imported by cve.new

    Latest catalog import, not the date we first saw this advisory.

What changed

Follow changes
  1. CVE · CVE-2026-126072

    Observed 2026-11-14T03:55:47.506Z · upstream updated 2026-11-14T03:06:53.260Z

    Prioritization updated

    before

    []

    after

    [
  {
    "source": "CISA-ADP",
    "type": "SSVC",
    "role": "CISA Coordinator",
    "timestamp": "2026-11-14T03:06:42.687546Z",
    "decisions": [
      {
        "name": "Exploitation",
        "value": "none"
      },
      {
        "name": "Automatable",
        "value": "no"
      },
      {
        "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.