Vulnerability-Lookup

CVE-2026-50570 (GCVE-0-2026-50570)

Vulnerability from cvelistv5 – Published: 2026-06-10 17:34 – Updated: 2026-06-10 18:37

Title

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

Summary

Fission is an open-source, Kubernetes-native serverless framework that simplifies the deployment of functions and applications on Kubernetes. Prior to version 1.25.0, Fission added PodSpec safety validation for tenant-facing Environment and Function CRDs (ValidatePodSpecSafety / ValidateContainerSafety admission webhook + sanitizeContainerSecurityContext executor merge layer), but the capability check was implemented as a fixed denylist of six Linux capabilities (SYS_ADMIN, NET_ADMIN, SYS_PTRACE, SYS_MODULE, DAC_READ_SEARCH, DAC_OVERRIDE). The denylist omitted CAP_SYS_TIME, among others. As a result, a tenant who could create a Function or Environment CRD could request securityContext.capabilities.add: ["SYS_TIME"], pass Fission's admission validation and merge-layer sanitization, and run attacker-controlled code with CAP_SYS_TIME in the resulting function or runtime container. This issue has been patched in version 1.25.0.

Severity

8.5 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-06-10 18:31 UTC

CWE

CWE-269 - Improper Privilege Management
CWE-732 - Incorrect Permission Assignment for Critical Resource

Assigner

GitHub_M mitre root

References

3 references

URL	Tags
https://github.com/fission/fission/security/advis…	x_refsource_CONFIRM
https://github.com/fission/fission/pull/3465	x_refsource_MISC
https://github.com/fission/fission/releases/tag/v1.25.0	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
fission	fission	Affected: < 1.25.0	guessed

Show details on NVD website

JSON

To clipboard

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                "id": "CVE-2026-50570",
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FKIE_CVE-2026-50570

Vulnerability from fkie_nvd - Published: 2026-06-10 18:17 - Updated: 2026-06-17 10:57

Severity

8.5 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/fission/fission/pull/3465
	security-advisories@github.com	https://github.com/fission/fission/releases/tag/v1.25.0
	security-advisories@github.com	https://github.com/fission/fission/security/advisories/GHSA-qf5v-m7p4-95rp

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "fission",
          "vendor": "fission",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 1.25.0"
            }
          ]
        }
      ],
      "source": "security-advisories@github.com"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Fission is an open-source, Kubernetes-native serverless framework that simplifies the deployment of functions and applications on Kubernetes. Prior to version 1.25.0, Fission added PodSpec safety validation for tenant-facing Environment and Function CRDs (ValidatePodSpecSafety / ValidateContainerSafety admission webhook + sanitizeContainerSecurityContext executor merge layer), but the capability check was implemented as a fixed denylist of six Linux capabilities (SYS_ADMIN, NET_ADMIN, SYS_PTRACE, SYS_MODULE, DAC_READ_SEARCH, DAC_OVERRIDE). The denylist omitted CAP_SYS_TIME, among others. As a result, a tenant who could create a Function or Environment CRD could request securityContext.capabilities.add: [\"SYS_TIME\"], pass Fission\u0027s admission validation and merge-layer sanitization, and run attacker-controlled code with CAP_SYS_TIME in the resulting function or runtime container. This issue has been patched in version 1.25.0."
    }
  ],
  "id": "CVE-2026-50570",
  "lastModified": "2026-06-17T10:57:43.453",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "LOW",
          "baseScore": 8.5,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "NONE",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "CHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L",
          "version": "3.1"
        },
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        "impactScore": 4.7,
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
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    "ssvcV203": [
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            }
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          "timestamp": "2026-06-10T18:31:08.293816Z",
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}

GHSA-QF5V-M7P4-95RP

Vulnerability from github – Published: 2026-07-28 20:12 – Updated: 2026-07-28 20:12

Summary

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

Details

Fission v1.24.0 added PodSpec safety validation for tenant-facing Environment and Function CRDs (ValidatePodSpecSafety / ValidateContainerSafety admission webhook + sanitizeContainerSecurityContext executor merge layer), but the capability check was implemented as a fixed denylist of six Linux capabilities (SYS_ADMIN, NET_ADMIN, SYS_PTRACE, SYS_MODULE, DAC_READ_SEARCH, DAC_OVERRIDE). The denylist omitted CAP_SYS_TIME, among others. As a result, a tenant who could create a Function or Environment CRD could request securityContext.capabilities.add: ["SYS_TIME"], pass Fission's admission validation and merge-layer sanitization, and run attacker-controlled code with CAP_SYS_TIME in the resulting function or runtime container.

Demonstrated consequence: cross-tenant node integrity damage via CAP_SYS_TIME. The Linux real-time clock is not namespaced — time namespaces virtualize only MONOTONIC and BOOTTIME, never REALTIME — so a tenant container holding CAP_SYS_TIME could call clock_settime(CLOCK_REALTIME) and rewrite the shared node wall clock. That corrupts TLS / certificate validity windows, Kubernetes lease renewal, token expiry, scheduling, and time-series for every workload on the node.

The denylist also omitted SYS_RAWIO, BPF, SYS_RESOURCE, and MAC_ADMIN. Those are documented as evidence that the denylist is structurally incomplete (their practical impact is kernel-, LSM-, or device-cgroup-dependent and is not exercised in this report).

The deeper structural problem: a denylist on capabilities.add cannot constrain capabilities the OCI runtime grants by default — DAC_OVERRIDE is in the OCI default cap set and reaches the container regardless of any add check, partially mooting the denylist for its own entries. A capability allowlist (with drop:["ALL"] to remove the default set) is the only model that addresses both problems.

Affected

Project: github.com/fission/fission
Versions: <= 1.24.0
Audited commits: v1.24.0 tag (ce617120) and current HEAD at audit time
Component: pkg/apis/core/v1/podspec_safety.go (dangerousCapabilities) and pkg/executor/util/merge.go (dangerousMergeContainerCapabilities)
Pre-condition: cluster does not enforce a restrictive Pod Security Admission (PSA) profile on the function-pod namespace. With PSA restricted in force the API server's PodSecurity admission rejects the pod at creation and this finding does not apply. Fission added its own PodSpec validation precisely because it cannot assume PSA enforcement.

Fix section (paste into the Fix / Patches field)

Fixed in v1.25.0 by:

PR #3465 (commit 2569b42b) — replace the denylist with a PSA-restricted allowlist (NET_BIND_SERVICE only) at both enforcement layers:
pkg/apis/core/v1/podspec_safety.go — ValidateContainerSafety now rejects any capabilities.add entry not in allowedCapabilities. The container check is invoked from ValidatePodSpecSafety for every PodSpec container / init-container and from Environment.validateForAdmission for the bare Runtime.Container / Builder.Container.
pkg/executor/util/merge.go — sanitizeContainerSecurityContext filters capabilities.add through the same allowlist at every merge site (poolmgr / newdeploy / container executor / builder).
The same PR adds 21 bounded CEL XValidation rules covering the cheap pod-level invariants (hostNetwork / hostPID / hostIPC / serviceAccountName / serviceAccount override) on FunctionSpec, Runtime, and Builder, plus the bare-Container SecurityContext checks (privileged != true, allowPrivilegeEscalation != true, capabilities.add ⊆ {NET_BIND_SERVICE}) on Runtime and Builder. The API server now short-circuits those attack vectors per CRD apply before the webhook is invoked. Per-container PodSpec iteration stays in the webhook because it exceeds the API server's CEL cost budget.
The same PR also adds two forward-compat regression guards in pkg/apis/core/v1/podspec_safety_test.go:
TestAllTenantContainerSurfacesAreValidated walks every CRD root type via reflection and fails if any reachable *apiv1.PodSpec or *apiv1.Container field is missing from the hand-maintained known-covered set.
TestTenantContainerSurfaces_RejectSysAdmin end-to-end exercises each covered surface and asserts ValidateForAdmission rejects a SYS_ADMIN injection at that exact path.

Not addressed in v1.25.0

The advisory's structural recommendation to force capabilities.drop: ["ALL"] at the merge layer is not part of this fix. Fission's own sidecar containers (fission-fetcher, builder) were authored against the OCI default capability set and need a per-container cap audit before drop:["ALL"] can be applied uniformly. The allowlist on capabilities.add closes the demonstrated CAP_SYS_TIME impact; the OCI-default-cap concern (which the advisory itself marks as conditional / not demonstrated) is tracked separately.

Severity

8.5 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.24.0"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/fission/fission"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.25.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-50570"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-269",
      "CWE-732"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-28T20:12:45Z",
    "nvd_published_at": "2026-06-10T18:17:13Z",
    "severity": "HIGH"
  },
  "details": "Fission v1.24.0 added PodSpec safety validation for tenant-facing Environment and Function CRDs (`ValidatePodSpecSafety` / `ValidateContainerSafety` admission webhook + `sanitizeContainerSecurityContext` executor merge layer), but the\ncapability check was implemented as a fixed **denylist of six Linux capabilities** (SYS_ADMIN, NET_ADMIN, SYS_PTRACE, SYS_MODULE, DAC_READ_SEARCH, DAC_OVERRIDE). The denylist omitted **CAP_SYS_TIME**, among others. As a result, a tenant\nwho could create a Function or Environment CRD could request `securityContext.capabilities.add: [\"SYS_TIME\"]`, pass Fission\u0027s admission validation and merge-layer sanitization, and run attacker-controlled code with `CAP_SYS_TIME` in the\nresulting function or runtime container.\n\nDemonstrated consequence: cross-tenant node integrity damage via `CAP_SYS_TIME`. The Linux real-time clock is not namespaced \u2014 time namespaces virtualize only `MONOTONIC` and `BOOTTIME`, never `REALTIME` \u2014 so a tenant container holding\n`CAP_SYS_TIME` could call `clock_settime(CLOCK_REALTIME)` and rewrite the shared node wall clock. That corrupts TLS / certificate validity windows, Kubernetes lease renewal, token expiry, scheduling, and time-series for every workload on\nthe node.\n\nThe denylist also omitted `SYS_RAWIO`, `BPF`, `SYS_RESOURCE`, and `MAC_ADMIN`. Those are documented as evidence that the denylist is structurally incomplete (their practical impact is kernel-, LSM-, or device-cgroup-dependent and is not\nexercised in this report).\n\nThe deeper structural problem: a denylist on `capabilities.add` cannot constrain capabilities the OCI runtime grants by default \u2014 `DAC_OVERRIDE` is in the OCI default cap set and reaches the container regardless of any `add` check,\npartially mooting the denylist for its own entries. A capability allowlist (with `drop:[\"ALL\"]` to remove the default set) is the only model that addresses both problems.\n\n### Affected\n\n- Project: `github.com/fission/fission`\n- Versions: `\u003c= 1.24.0`\n- Audited commits: v1.24.0 tag (`ce617120`) and current HEAD at audit time\n- Component: `pkg/apis/core/v1/podspec_safety.go` (`dangerousCapabilities`) and `pkg/executor/util/merge.go` (`dangerousMergeContainerCapabilities`)\n- Pre-condition: cluster does not enforce a restrictive Pod Security Admission (PSA) profile on the function-pod namespace. With PSA `restricted` in force the API server\u0027s PodSecurity admission rejects the pod at creation and this\nfinding does not apply. Fission added its own PodSpec validation precisely because it cannot assume PSA enforcement.\n\n\nFix section (paste into the Fix / Patches field)\n\nFixed in [v1.25.0](https://github.com/fission/fission/releases/tag/v1.25.0) by:\n\n- [PR #3465](https://github.com/fission/fission/pull/3465) (commit [`2569b42b`](https://github.com/fission/fission/commit/2569b42b)) \u2014 replace the denylist with a PSA-restricted allowlist (`NET_BIND_SERVICE` only) at both enforcement\nlayers:\n  - `pkg/apis/core/v1/podspec_safety.go` \u2014 `ValidateContainerSafety` now rejects any `capabilities.add` entry not in `allowedCapabilities`. The container check is invoked from `ValidatePodSpecSafety` for every PodSpec container /\ninit-container and from `Environment.validateForAdmission` for the bare `Runtime.Container` / `Builder.Container`.\n  - `pkg/executor/util/merge.go` \u2014 `sanitizeContainerSecurityContext` filters `capabilities.add` through the same allowlist at every merge site (poolmgr / newdeploy / container executor / builder).\n- The same PR adds 21 bounded CEL `XValidation` rules covering the cheap pod-level invariants (`hostNetwork` / `hostPID` / `hostIPC` / `serviceAccountName` / `serviceAccount` override) on `FunctionSpec`, `Runtime`, and `Builder`, plus\nthe bare-Container `SecurityContext` checks (`privileged != true`, `allowPrivilegeEscalation != true`, `capabilities.add \u2286 {NET_BIND_SERVICE}`) on `Runtime` and `Builder`. The API server now short-circuits those attack vectors per CRD\napply before the webhook is invoked. Per-container PodSpec iteration stays in the webhook because it exceeds the API server\u0027s CEL cost budget.\n- The same PR also adds two forward-compat regression guards in `pkg/apis/core/v1/podspec_safety_test.go`:\n  - `TestAllTenantContainerSurfacesAreValidated` walks every CRD root type via reflection and fails if any reachable `*apiv1.PodSpec` or `*apiv1.Container` field is missing from the hand-maintained known-covered set.\n  - `TestTenantContainerSurfaces_RejectSysAdmin` end-to-end exercises each covered surface and asserts `ValidateForAdmission` rejects a `SYS_ADMIN` injection at that exact path.\n\n### Not addressed in v1.25.0\n\nThe advisory\u0027s structural recommendation to force `capabilities.drop: [\"ALL\"]` at the merge layer is **not** part of this fix. Fission\u0027s own sidecar containers (`fission-fetcher`, builder) were authored against the OCI default capability\nset and need a per-container cap audit before `drop:[\"ALL\"]` can be applied uniformly. The allowlist on `capabilities.add` closes the demonstrated `CAP_SYS_TIME` impact; the OCI-default-cap concern (which the advisory itself marks as\nconditional / not demonstrated) is tracked separately.",
  "id": "GHSA-qf5v-m7p4-95rp",
  "modified": "2026-07-28T20:12:45Z",
  "published": "2026-07-28T20:12:45Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/fission/fission/security/advisories/GHSA-qf5v-m7p4-95rp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-50570"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fission/fission/pull/3465"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fission/fission/commit/2569b42bfadbcb7d78b55a00a60f77937e522699"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/fission/fission"
    },
    {
      "type": "WEB",
      "url": "https://github.com/fission/fission/releases/tag/v1.25.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:L",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Fission: Incomplete capability denylist in Environment/Function PodSpec validation allows tenant-added CAP_SYS_TIME and cross-tenant node wall-clock corruption"
}

Sightings

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Action not permitted

CVE-2026-50570 (GCVE-0-2026-50570)

FKIE_CVE-2026-50570

GHSA-QF5V-M7P4-95RP

Affected

Not addressed in v1.25.0

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Sightings

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