CVE-2026-56858VulnerabilityPublished 11 Nov 2026

Kubernetes: Previously, pathological inputs could close an unescaped '/' early, allowing for attack-controlled data to

Affects kubernetesSource GCVE Database

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Authoritative record:CVE-2026-56858· Medium 6.1

Not known to be exploited · CVSS 6.1 Medium : upgrade to 1.34.13-r2 when convenient.

Data as of 11 Nov 2026, 04:17 UTC

CVSS 3.1 base score

6.1Medium

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

Patch: Available – fixed in 1.34.13-r2, 4.1.6-r1

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

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Changed
Confidentiality: Low
Integrity: Low
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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on 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 13 Aug 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 10 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

Upgrade kubernetes to 1.34.13-r2; argo-workflows to 4.1.6-r1.

Affected software

Product	Affected	Fixed in
CleanStartkubernetes`pkg:apk/cleanstart/kubernetes`Other threats	Affected <1.34.13-r2	Fixed in 1.34.13-r2
CleanStartargo-workflows`pkg:apk/cleanstart/argo-workflows`Other threats	Affected <4.1.6-r1	Fixed in 4.1.6-r1

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

AI-suggested

A patch is available and has been released in Kubernetes versions 1.34.13-r2 and 4.1.6-r1. Users should upgrade to these versions or later to remediate this vulnerability. No additional mitigation steps are specified by the vendor advisory.

Description

CVE-2026-56858 is a vulnerability in Kubernetes where certain pathological inputs could prematurely close an unescaped '/' character. This flaw allows an attacker to inject arbitrary content, potentially leading to cross-site scripting (XSS). The issue affects multiple Kubernetes packages and has been addressed in versions 1.34.13-r2 and 4.1.6-r1.

Impact

Successful exploitation of this vulnerability could allow an attacker to inject arbitrary content via specially crafted inputs, potentially resulting in cross-site scripting (XSS). This could lead to limited confidentiality and integrity impacts, but no availability impact is indicated. The CVSS score of 6.1 reflects a medium severity with network attack vector, low attack complexity, no privileges required, and user interaction required.

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Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2026, 04:17 UTC

Technical details

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