Active Storage makes it simple to upload and reference files in cloud services and attach those files to Active Record objects. From 8.0 until 8.0.5.2 and 8.1.4.1, when Active Storage serves a file through its proxy controllers, ActiveStorage::Streaming#send_blob_stream handles an error from the storage service by calling head to send a 404 or 500 response. If the error occurs after the first chunk has been written, the response is already committed, and head replaces the response body while the server is still reading the original ActionController::Live buffer. That buffer is never closed, so the server thread handling the request blocks until the process restarts. Repeated failed downloads could exhaust the server's threads, possibly resulting in a DoS vulnerability. Applications are affected when they store files on a service that streams a download in several requests, such as Amazon S3, an S3-compatible service or Google Cloud Storage, and draw Active Storage's default routes. The proxy routes are drawn whether or not proxy mode is the default for the application. A file deleted while it is being served, or any other storage error partway through a download, triggers the condition. This issue is fixed in versions 8.1.4.1 and 8.0.5.2.
CVE-2026-126071
“—” beside the score: it is equal to the CVSS score beside it.
Score 5.3 from GitHub Security Advisory (severity: MODERATE) published 2026-11-10. A secondary CVSS source baseline 5.3; sources differ by 0.0.
Also known asEUVD-2026-122995 (ENISA EUVD) · GHSA-4v2w-w6g6-f8f8 (GitHub Security Advisories)Source: ENISA EUVD
- Lower severity and no public exploit yet
A fix is available — apply it.
- CVSS v3
- 5.3
- EG Score
- 5.3MEDIUMhigh confidence
- EG Risk
- 24EG Risk 24/100
EG Risk is EchelonGraph's 0–100 priority score. It fuses impact severity (EG Severity, the CVSS base score, never the KEV-floored or EPSS-lifted EG Score) with real-world exploitation and automatability, under weights EchelonGraph set by hand, so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner.
How it’s computed (value × EchelonGraph’s weight)Severity53% × 45%Impact severity (EG Severity): CVSS 5.3 of 10. Never the KEV-floored or EPSS-lifted EG Score.Exploitation0.4% × 40%FIRST EPSS: the 30-day exploitation probability when EchelonGraph scored this CVE.Automatability0% × 15%CISA's SSVC Automatable value: no (Vulnrichment).SSVC (CISA's decision table, applied by EchelonGraph): Track at every mission impact level.Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE.Action: A fix is available. Apply it within your standard update timelines. - EPSS PROB
- 0.4%
- EPSS %ILE
- 39th
- KEV
- Not listed
What the EG score is made of (scorer v4.0: the three questions the 0–10 score mixes, published apart · methodology)
The EG score (5.3): severity, escalated by confirmed exploitation. This CVE's 5.3 is its impact severity (EG Severity), not escalated.
- EG Severity
- 5.3 MEDIUMCVSS-B, impact only: no KEV listing, EPSS or EG-KEV tier raises it.GitHub Security Advisory CVSS
- EG Likelihood
- 0.4% within 30 daysSource: FIRST EPSS (model v2026.06.15, score date 2026-11-13). FIRST's exploitation probability, not an EchelonGraph model.
- Confirmed exploitation
- None on record (CISA KEV, EG-KEV Tier 1)Reported apart from the likelihood: an observed fact, not a probability.
- EG Priority
- SSVC Track at medium mission impactTrack at every mission impact level.CISA BOD 26-04: 60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.Each input and its source, and whom BOD 26-04 binds: the SSVC and BOD 26-04 blocks below.
SSVC (CISA's decision table, applied by EchelonGraph)Track at every mission impact level.
A fix is available. Apply it within your standard update timelines.
Exploitation none (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). All three are CISA's SSVC values (Vulnrichment). EchelonGraph applied CISA's decision table to them; CISA publishes SSVC inputs and the table, not a decision for each CVE. Mission impact is CISA's Mission & Well-being decision point, and only you can judge it. CISA's table makes it high when Mission Prevalence is Essential — the vulnerable component "directly provides capabilities that constitute at least one MEF for at least one entity" (MEF: mission essential function) — or when Public Well-Being Impact is Irreversible: "multiple fatalities are likely", the cyber-physical system "is likely lost or destroyed", "extreme or serious externalities" are imposed on other parties, or social systems such as elections or the financial grid "are destabilized and potentially collapse". CISA's decision table
BOD 26-04 (CISA's remediation timeline, Table 1)60 days if the affected system is publicly exposed; Fix on system upgrade if it is not.
The score's inputs: In CISA KEV no (CISA's KEV catalog) · Automatable no (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Whether your system is publicly exposed is yours to answer. BOD 26-04 binds US Federal Civilian Executive Branch agencies; for anyone else it is CISA's published timeline, a reference rather than an obligation. The directive · how EchelonGraph applies it
Published
November 10, 2026
Last Modified
November 13, 2026
Advisory Details (5)
Auto-updated Nov 13, 20268.1.4.1
Patch available: rails/rails v8.1.4.1
https://github.com/rails/rails/releases/tag/v8.1.4.18.0.5.2
Patch available: rails/rails v8.0.5.2
https://github.com/rails/rails/releases/tag/v8.0.5.2commit 655b4442de13 (rails/rails)
Fix landed in rails/rails commit 655b4442de13 — awaiting tagged release
https://github.com/rails/rails/commit/655b4442de136a3701334607f634d698bf9d5b82commit 3c67a693fb21 (rails/rails)
Fix landed in rails/rails commit 3c67a693fb21 — awaiting tagged release
https://github.com/rails/rails/commit/3c67a693fb21870ecb1222e3da59d5c491a62009Possible DoS vulnerability in Active Storage proxy mode via storage errors during streaming · Advisory · rails/rails · GitHub
https://github.com/rails/rails/security/advisories/GHSA-4v2w-w6g6-f8f8Vendor Advisories for CVE-2026-126071(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Patch Availability(2)
| Vendor / Ecosystem | Fix (by version range) / Patch | Released | Source |
|---|---|---|---|
| rubygems | activestorage @ 8.1.4.1 (fixes >= 8.1.0.beta1, < 8.1.4.1) | — | ghsa |
| rubygems | activestorage @ 8.0.5.2 (fixes >= 8.0.0.beta1, < 8.0.5.2) | — | ghsa |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Affected Packages
(1 across 1 ecosystem)
RubyGems(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| activestorage | 8.0.0 ... 8.0.5.1 (13 versions) |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 9× in last 7d / 9× in last 30d)
Each row is a time one of our pipelines fetched, updated or re-scored this CVE. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed its CVE.org record (CNA or CISA ADP). An arrow marks a change the record states ("CVSS v3 → 9.1"); EPSS and GHSA rows show the values recorded at that time, not what changed (EPSS values are rounded; hover one for the exact figures). "EchelonGraph re-scored" is our own recompute of this CVE's score, not an update from a source, and is not counted in the refreshes above. Most recent first.
- 2026-11-13 17:31 UTCEchelonGraph re-scored
- 2026-11-13 17:31 UTCGHSA enrichmentGHSA-4v2w-w6g6-f8f8 · GitHub severity MODERATE · GitHub CVSS 5.3
- 2026-11-13 16:50 UTCEPSS rescoreEPSS 0.4% · 39th percentile
- 2026-11-13 16:29 UTCEchelonGraph re-scored
- 2026-11-13 16:29 UTCGHSA enrichmentGHSA-4v2w-w6g6-f8f8 · GitHub severity MODERATE · GitHub CVSS 5.3
- 2026-11-12 22:32 UTCEchelonGraph re-scored
- 2026-11-12 22:32 UTCGHSA enrichmentGHSA-4v2w-w6g6-f8f8 · GitHub severity MODERATE · GitHub CVSS 5.3
- 2026-11-12 16:33 UTCEPSS rescoreEPSS 0.4% · 39th percentile
- 2026-11-11 16:38 UTCEPSS rescoreEPSS 0.4% · 39th percentile
- 2026-11-10 22:00 UTCENISA EUVD ID recordedEUVD-2026-122995 · Source: ENISA EUVD
- 2026-11-10 21:33 UTCEchelonGraph re-scored
- 2026-11-10 21:32 UTCGHSA enrichmentGHSA-4v2w-w6g6-f8f8 · GitHub severity MODERATE · GitHub CVSS 5.3
- 2026-11-10 20:46 UTCMITRE cvelistV5first tracked
- 2026-11-10 20:46 UTCEchelonGraph re-scoredFirst assessed: 5.3 MEDIUM
Related CVEs(same product + same CWE)
Same product
10 shownRubyGems:activestorage
Frequently asked(5)
What is CVE-2026-126071?
When was the CVE record for CVE-2026-126071 published?
Is CVE-2026-126071 actively exploited?
What is the CVSS score of CVE-2026-126071?
How do I remediate CVE-2026-126071?
Dependency Blast Radius
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