VulnerabilityPublished 28 Jul 2026

CVE-2026-50570: Fission · Incomplete capability denylist in Environment/Function PodSpec validation allows tenant-added CAP_SYS_TIME and cross-tenant node wall-clock corruption

Affects github.com/fission/fissionSource GCVE Database

Not known to be exploited · CVSS 8.5 High : upgrade to 1.25.0 soon.

Data as of 27 Oct 2026, 05:11 UTC

CVSS 3.1 base score

8.5High

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 19% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.25.0

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

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

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: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
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: 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: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 28 Jul 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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 github.com/fission/fission to 1.25.0.

Affected software

Product	Affected	Fixed in
Gogithub.com/fission/fission	Affected <1.25.0	Fixed in 1.25.0

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

AI-suggested

A fix is available in Fission version 1.25.0, which replaces the capability denylist with a restrictive allowlist and adds admission webhook and API server CEL validation rules to reject unsafe capability additions. Users should upgrade to v1.25.0 or later. Additionally, enforcing a restrictive Pod Security Admission (PSA) profile such as 'restricted' on the function-pod namespace prevents this vulnerability by rejecting pods with unsafe capabilities at creation. The vendor does not currently enforce capabilities.drop:["ALL"] due to sidecar compatibility but plans further improvements.

Description

Fission versions up to 1.24.0 implemented PodSpec validation with a fixed denylist of Linux capabilities but omitted CAP_SYS_TIME. This omission allows tenants to add CAP_SYS_TIME to their function or environment containers, enabling them to alter the node's real-time clock. Since the Linux real-time clock is shared across the node, this can corrupt time-dependent operations for all workloads on that node. The vulnerability is fixed in Fission 1.25.0 by replacing the denylist with a restrictive allowlist for capabilities. The issue does not apply if a restrictive Pod Security Admission profile is enforced on the function-pod namespace.

Impact

An attacker tenant able to create Function or Environment CRDs can gain CAP_SYS_TIME in their container, allowing them to modify the node's real-time clock. This compromises node-wide time integrity, disrupting TLS and certificate validation, Kubernetes lease renewals, token expirations, scheduling, and time-series data for all workloads on the node. This represents a high integrity impact with limited availability impact. Other omitted capabilities in the denylist may pose additional risks but were not demonstrated.

Summary

Fission v1.24.0 introduced PodSpec safety validation for tenant-facing Environment and Function CRDs using a denylist of six Linux capabilities. However, the denylist omitted CAP_SYS_TIME, allowing tenants to request this capability in their container security context. With CAP_SYS_TIME, tenant containers can call clock_settime(CLOCK_REALTIME) to modify the node's shared wall clock, affecting TLS validity, Kubernetes leases, token expiry, scheduling, and time-series data for all node workloads. The denylist also omitted other capabilities, indicating structural incompleteness. The underlying problem is that the denylist approach cannot constrain default OCI runtime capabilities. The fix in v1.25.0 replaces the denylist with a strict allowlist (NET_BIND_SERVICE only) enforced at multiple layers, including admission webhook and executor merge layer, and adds CEL validation rules to reject unsafe configurations. The fix does not yet enforce capabilities.drop:["ALL"] due to compatibility concerns with Fission sidecar containers.

CWE-269Improper Privilege Management (opens in a new tab)
Class weaknessLikelihood of exploit: MediumOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
Architecture and Design · Operation
Very carefully manage the setting, management, and handling of privileges. Explicitly manage trust zones in the software.
Architecture and Design · Separation of Privilege
Follow the principle of least privilege when assigning access rights to entities in a software system.
Architecture and Design · Separation of Privilege
Consider following the principle of separation of privilege. Require multiple conditions to be met before permitting access to a system resource.
OWASP Cheat Sheets
Docker Security (opens in a new tab)
Third Party Javascript Management (opens in a new tab)
Virtual Patching (opens in a new tab)
Secure Design Principles (opens in a new tab)
OWASP ASVS 4.0.3
V1.4.4 (opens in a new tab)
V1.4.5 (opens in a new tab)
V1.10.1 (opens in a new tab)
Attack patterns
Restful Privilege Elevation (opens in a new tab)
Privilege Abuse (opens in a new tab)
Privilege Escalation (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).
CWE-732Incorrect Permission Assignment for Critical Resource (opens in a new tab)
Class weaknessLikelihood of exploit: HighOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.
Implementation
When using a critical resource such as a configuration file, check to see if the resource has insecure permissions (such as being modifiable by any regular user), and generate an error or even exit the software if there is a possibility that the resource could have been modified by an unauthorized party.
Architecture and Design
Divide the software into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully defining distinct user groups, privileges, and/or roles. Map these against data, functionality, and the related resources. Then set the permissions accordingly.
Architecture and Design · Operation · Sandbox or Jail
Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software.
OWASP Cheat Sheets
REST Assessment (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V4.3.3 (opens in a new tab)
V8.3.8 (opens in a new tab)
V13.4.2 (opens in a new tab)
Attack patterns
Accessing Functionality Not Properly Constrained by ACLs (opens in a new tab)
Directory Indexing (opens in a new tab)
Using Malicious Files (opens in a new tab)
Exploiting Incorrectly Configured Access Control Security Levels (opens in a new tab)
Signing Malicious Code (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 29 Jul 2026, 11:37 UTC

WeaknessesCWE-269, CWE-732

Technical details

References

Community reviews

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