CVE-2026-126081VulnerabilityPublished 12 Nov 2026Updated 13 Nov 2026

Rails: Prior to 8.1.4.1 and 8.0.5.2, ActionController::Parameters#each_key delegates to the internal

Affects railsSource GCVE Database

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Mentioned vulnerabilities

CVE-2020-8164

Authoritative record:CVE-2026-126081· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in 8.1.4.1 : patch rails soon.

Data as of 13 Nov 2026, 22:24 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (GitHub_M)	CVSS 3.1	7.5

Patch: Available – fixed in 8.1.4.1

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 10 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 13 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Ubuntu 26.10rails`pkg:deb/ubuntu/rails?arch=source&distro=stonking`Other threats	Affected =2:7.2.3+dfsg-2 =2:7.2.3.2+dfsg-2	Fixed in–
Ubuntu 26.04 LTSrails`pkg:deb/ubuntu/rails?arch=source&distro=resolute`Other threats	Affected =2:7.2.2.1+dfsg-7 =2:7.2.2.2+dfsg-2 =2:7.2.3+dfsg-2	Fixed in–
Ubuntu 24.04 LTSrails`pkg:deb/ubuntu/rails?arch=source&distro=noble`Other threats	Affected =2:6.1.7.3+dfsg-2build1 =2:6.1.7.3+dfsg-3	Fixed in–
Ubuntu Pro 22.04 LTSrails`pkg:deb/ubuntu/rails?arch=source&distro=esm-apps/jammy`Other threats	Affected =2:6.0.3.7+dfsg-2 =2:6.1.4.1+dfsg-8ubuntu2 =2:6.1.4.1+dfsg-8ubuntu2+esm1	Fixed in–
Ubuntu Pro 20.04 LTSrails`pkg:deb/ubuntu/rails?arch=source&distro=esm-apps/focal`Other threats	Affected =2:5.2.2.1+dfsg-1ubuntu1 =2:5.2.3+dfsg-3 =2:5.2.3+dfsg-3ubuntu0.1~esm1	Fixed in–
Ubuntu Pro 18.04 LTSrails`pkg:deb/ubuntu/rails?arch=source&distro=esm-apps/bionic`Other threats	Affected 2:4.2.9-2 – 2:4.2.10-0ubuntu4+esm2 5 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Rails to version 8.1.4.1 or 8.0.5.2 or later, where this issue is fixed. No other mitigation is indicated. If upgrading is not immediately possible, review application code to ensure it does not pass the return value of each_key with a block to mass assignment methods. Patch status is confirmed fixed in the specified versions.

Description

A vulnerability in Rails prior to versions 8.1.4.1 and 8.0.5.2 affects ActionController::Parameters#each_key. When called with a block, it returns an internal hash that does not respond to permitted?, allowing mass assignment to accept unpermitted attributes without raising an error. This could enable a remote unauthenticated attacker to set unauthorized attributes if the application passes the return value of each_key to mass assignment. This issue is an incomplete fix of CVE-2020-8164 and is resolved in the specified fixed versions.

Impact

The vulnerability allows remote unauthenticated attackers to bypass attribute whitelisting in mass assignment by exploiting the behavior of ActionController::Parameters#each_key. This could lead to unauthorized modification of sensitive attributes, such as authorization flags, potentially compromising application security. However, exploitation requires the application to explicitly pass the return value of each_key with a block to mass assignment methods. Rails framework code itself does not do this.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 13 Nov 2026, 22:24 UTC

Technical details

References

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