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CVE-2026-44300

OpenCost ServiceKey Endpoint Unauthorized Credential Overwrite/Injection

8.8 HighFix available

OpenCost provides cost monitoring for Kubernetes workloads and cloud costs. Prior to 1.121.0, the POST /serviceKey endpoint in pkg/costmodel/router.go allows a network client to invoke AddServiceKey without mandatory authentication and submit an arbitrary key form value that is written to the GCP service-account key.json file returned by GetGCPAuthSecretFilePath in core/pkg/env/core.go. The attacker controls the file contents but not the CONFIG_PATH-derived directory, the key.json filename, or the file mode. Replacing the credential contents can disrupt GCP cost collection or cause OpenCost to use attacker-selected credentials, and the wildcard Access-Control-Allow-Origin response permits browser-assisted requests when the service is reachable from a browser. This issue is fixed in version 1.121.0.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
High
Availability
High

Exploit likelihood

0.75%Up 0.3 points since Sep 16, 2026
90%50%10%1%

What each source reports

CVE List Score used 8.8

OpenCost ServiceKey Endpoint Unauthorized Credential Overwrite/Injection

OpenCost provides cost monitoring for Kubernetes workloads and cloud costs. Prior to 1.121.0, the POST /serviceKey endpoint in pkg/costmodel/router.go allows a network client to invoke AddServiceKey without mandatory authentication and submit an arbitrary key form value that is written to the GCP service-account key.json file returned by GetGCPAuthSecretFilePath in core/pkg/env/core.go. The attacker controls the file contents but not the CONFIG_PATH-derived directory, the key.json filename, or the file mode. Replacing the credential contents can disrupt GCP cost collection or cause OpenCost to use attacker-selected credentials, and the wildcard Access-Control-Allow-Origin response permits browser-assisted requests when the service is reachable from a browser. This issue is fixed in version 1.121.0.

Record
CVE-2026-44300
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-20, CWE-309
Updated
2026-11-02
EUVDEUVD-2026-78874 8.8

OpenCost provides cost monitoring for Kubernetes workloads and cloud costs. Prior to 1.121.0, the POST /serviceKey endpoint in pkg/costmodel/router.go allows a network client to invoke AddServiceKey without mandatory authentication and submit an arbitrary key form value that is written to the GCP service-account key.json file returned by GetGCPAuthSecretFilePath in core/pkg/env/core.go. The attacker controls the file contents but not the CONFIG_PATH-derived directory, the key.json filename, or the file mode. Replacing the credential contents can disrupt GCP cost collection or cause OpenCost to use attacker-selected credentials, and the wildcard Access-Control-Allow-Origin response permits browser-assisted requests when the service is reachable from a browser. This issue is fixed in version 1.121.0.

Record
EUVD-2026-78874
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-wmj8-9953-vff5 8.8

OpenCost ServiceKey Endpoint Unauthorized Credential Overwrite/Injection

Summary

OpenCost contains an unauthenticated file write vulnerability in the /serviceKey endpoint that allows remote attackers to overwrite the GCP service account key file without authentication. This can lead to service disruption, credential theft, and potential privilege escalation within Kubernetes clusters.

Affected Versions

  • OpenCost: All versions up to and including the latest release
  • Vulnerable File: pkg/costmodel/router.go (lines 365-379)
  • Vulnerable Endpoint: POST /serviceKey

Vulnerability Details

Root Cause

The AddServiceKey function in pkg/costmodel/router.go accepts user-supplied data via POST request and writes it directly to a file without any authentication or input validation:

func (a *Accesses) AddServiceKey(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
    w.Header().Set("Content-Type", "application/json")
    w.Header().Set("Access-Control-Allow-Origin", "*")  // Overly permissive CORS

    r.ParseForm()

    key := r.PostForm.Get("key")  // User-controlled input, no validation
    k := []byte(key)
    err := os.WriteFile(env.GetGCPAuthSecretFilePath(), k, 0644)  //  Direct file write
    if err != nil {
        fmt.Fprintf(w, "Error writing service key: %s", err)
    }

    w.WriteHeader(http.StatusOK)
}

File Path Determination (core/pkg/env/core.go):

func GetGCPAuthSecretFilePath() string {
    return GetPathFromConfig("key.json")
}

func GetPathFromConfig(fileName string) string {
    return filepath.Join(GetConfigPath(), fileName)
}

func GetConfigPath() string {
    return Get(ConfigPathEnvVar, DefaultConfigPath)  // Default: /var/configs
}

Security Issues

  1. No Authentication: Any network-accessible client can invoke the endpoint
  2. No Input Validation: User input is not validated as a valid GCP service account key
  3. Overly Permissive CORS: Access-Control-Allow-Origin: * allows cross-origin attacks
  4. Predictable File Path: File location controlled by CONFIG_PATH environment variable

Proof of Concept

Environment Setup

Prerequisites

  • Kubernetes cluster (tested on kind v1.30.0)
  • Helm 3.x
  • kubectl configured

Step 1: Create Namespace

kubectl create namespace opencost

Output:

namespace/opencost created

Step 2: Add OpenCost Helm Repository

helm repo add opencost https://opencost.github.io/opencost-helm-chart
helm repo update

Output:

"opencost" has been added to your repositories
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "opencost" chart repository
Update Complete. Happy Helming!

Step 3: Deploy OpenCost

helm install opencost opencost/opencost --namespace opencost \
  --set opencost.exporter.defaultClusterId=test-cluster \
  --set opencost.prometheus.internal.enabled=true \
  --set opencost.prometheus.internal.serviceName=kube-prometheus-stack-prometheus \
  --set opencost.prometheus.internal.namespaceName=monitoring \
  --set opencost.prometheus.internal.port=9090 \
  --set-string 'opencost.exporter.extraEnv.CONFIG_PATH=/tmp'

Key Configuration:

  • CONFIG_PATH=/tmp: Sets writable directory for file operations

Output:

NAME: opencost
LAST DEPLOYED: Sun Jan 18 00:39:21 2026
NAMESPACE: opencost
STATUS: deployed
REVISION: 1

Step 4: Verify Deployment

kubectl get pods -l app.kubernetes.io/instance=opencost -n opencost

Output:

NAME                      READY   STATUS    RESTARTS   AGE
opencost-db97bbcc-5q8cb   2/2     Running   0          44s

Step 5: Verify Service Accessibility

kubectl run curl-test --image=curlimages/curl --rm -i --restart=Never -- \
  curl -v http://opencost.opencost.svc.cluster.local:9003/healthz

Output:

< HTTP/1.1 200 OK
< Vary: Origin
< Date: Sat, 17 Jan 2026 16:32:07 GMT
< Content-Length: 0

Exploitation

####…

Record
GHSA-wmj8-9953-vff5
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-20, CWE-309
Updated
2026-11-02
NVD 8.8

OpenCost provides cost monitoring for Kubernetes workloads and cloud costs. Prior to 1.121.0, the POST /serviceKey endpoint in pkg/costmodel/router.go allows a network client to invoke AddServiceKey without mandatory authentication and submit an arbitrary key form value that is written to the GCP service-account key.json file returned by GetGCPAuthSecretFilePath in core/pkg/env/core.go. The attacker controls the file contents but not the CONFIG_PATH-derived directory, the key.json filename, or the file mode. Replacing the credential contents can disrupt GCP cost collection or cause OpenCost to use attacker-selected credentials, and the wildcard Access-Control-Allow-Origin response permits browser-assisted requests when the service is reachable from a browser. This issue is fixed in version 1.121.0.

Record
CVE-2026-44300
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-20, CWE-309
Updated
2026-11-02
OSV 8.8

OpenCost ServiceKey Endpoint Unauthorized Credential Overwrite/Injection

OpenCost provides cost monitoring for Kubernetes workloads and cloud costs. Prior to 1.121.0, the POST /serviceKey endpoint in pkg/costmodel/router.go allows a network client to invoke AddServiceKey without mandatory authentication and submit an arbitrary key form value that is written to the GCP service-account key.json file returned by GetGCPAuthSecretFilePath in core/pkg/env/core.go. The attacker controls the file contents but not the CONFIG_PATH-derived directory, the key.json filename, or the file mode. Replacing the credential contents can disrupt GCP cost collection or cause OpenCost to use attacker-selected credentials, and the wildcard Access-Control-Allow-Origin response permits browser-assisted requests when the service is reachable from a browser. This issue is fixed in version 1.121.0.

Record
CVE-2026-44300
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-20, CWE-309
Updated
2026-11-02
OSVGHSA-wmj8-9953-vff5 8.8

OpenCost ServiceKey Endpoint Unauthorized Credential Overwrite/Injection

Summary

OpenCost contains an unauthenticated file write vulnerability in the /serviceKey endpoint that allows remote attackers to overwrite the GCP service account key file without authentication. This can lead to service disruption, credential theft, and potential privilege escalation within Kubernetes clusters.

Affected Versions

  • OpenCost: All versions up to and including the latest release
  • Vulnerable File: pkg/costmodel/router.go (lines 365-379)
  • Vulnerable Endpoint: POST /serviceKey

Vulnerability Details

Root Cause

The AddServiceKey function in pkg/costmodel/router.go accepts user-supplied data via POST request and writes it directly to a file without any authentication or input validation:

func (a *Accesses) AddServiceKey(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
    w.Header().Set("Content-Type", "application/json")
    w.Header().Set("Access-Control-Allow-Origin", "*")  // Overly permissive CORS

    r.ParseForm()

    key := r.PostForm.Get("key")  // User-controlled input, no validation
    k := []byte(key)
    err := os.WriteFile(env.GetGCPAuthSecretFilePath(), k, 0644)  //  Direct file write
    if err != nil {
        fmt.Fprintf(w, "Error writing service key: %s", err)
    }

    w.WriteHeader(http.StatusOK)
}

File Path Determination (core/pkg/env/core.go):

func GetGCPAuthSecretFilePath() string {
    return GetPathFromConfig("key.json")
}

func GetPathFromConfig(fileName string) string {
    return filepath.Join(GetConfigPath(), fileName)
}

func GetConfigPath() string {
    return Get(ConfigPathEnvVar, DefaultConfigPath)  // Default: /var/configs
}

Security Issues

  1. No Authentication: Any network-accessible client can invoke the endpoint
  2. No Input Validation: User input is not validated as a valid GCP service account key
  3. Overly Permissive CORS: Access-Control-Allow-Origin: * allows cross-origin attacks
  4. Predictable File Path: File location controlled by CONFIG_PATH environment variable

Proof of Concept

Environment Setup

Prerequisites

  • Kubernetes cluster (tested on kind v1.30.0)
  • Helm 3.x
  • kubectl configured

Step 1: Create Namespace

kubectl create namespace opencost

Output:

namespace/opencost created

Step 2: Add OpenCost Helm Repository

helm repo add opencost https://opencost.github.io/opencost-helm-chart
helm repo update

Output:

"opencost" has been added to your repositories
Hang tight while we grab the latest from your chart repositories...
...Successfully got an update from the "opencost" chart repository
Update Complete. Happy Helming!

Step 3: Deploy OpenCost

helm install opencost opencost/opencost --namespace opencost \
  --set opencost.exporter.defaultClusterId=test-cluster \
  --set opencost.prometheus.internal.enabled=true \
  --set opencost.prometheus.internal.serviceName=kube-prometheus-stack-prometheus \
  --set opencost.prometheus.internal.namespaceName=monitoring \
  --set opencost.prometheus.internal.port=9090 \
  --set-string 'opencost.exporter.extraEnv.CONFIG_PATH=/tmp'

Key Configuration:

  • CONFIG_PATH=/tmp: Sets writable directory for file operations

Output:

NAME: opencost
LAST DEPLOYED: Sun Jan 18 00:39:21 2026
NAMESPACE: opencost
STATUS: deployed
REVISION: 1

Step 4: Verify Deployment

kubectl get pods -l app.kubernetes.io/instance=opencost -n opencost

Output:

NAME                      READY   STATUS    RESTARTS   AGE
opencost-db97bbcc-5q8cb   2/2     Running   0          44s

Step 5: Verify Service Accessibility

kubectl run curl-test --image=curlimages/curl --rm -i --restart=Never -- \
  curl -v http://opencost.opencost.svc.cluster.local:9003/healthz

Output:

< HTTP/1.1 200 OK
< Vary: Origin
< Date: Sat, 17 Jan 2026 16:32:07 GMT
< Content-Length: 0

Exploitation

####…

Record
GHSA-wmj8-9953-vff5
CVSS 4.0
8.8 HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-20, CWE-309
Updated
2026-11-02
OSVGO-2026-5974 No score

OpenCost ServiceKey Endpoint Unauthorized Credential Overwrite/Injection in github.com/opencost/opencost

OpenCost ServiceKey Endpoint Unauthorized Credential Overwrite/Injection in github.com/opencost/opencost

Record
GO-2026-5974
Updated
2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

  • Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
  • GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
  • GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
  • GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
  • GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
  • GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
  • GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
  • GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
  • GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
  • GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
  • GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
  • GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
  • GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
  • GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
  • GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
  • GO-2026-5933 GHSA-3g4q-2f67-2gvh
  • GO-2026-5934 GHSA-59qp-cfj3-rp64
  • GO-2026-5935 GHSA-7856-g3gv-9wq8
  • GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
  • GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
  • GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
  • GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
  • GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
  • GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
  • GO-2026-5942 CVE-2026-46600
  • GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
  • GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
  • GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
  • GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
  • GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
  • GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
  • GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
  • GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
  • GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
  • GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
  • GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
  • GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
  • GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
  • GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
  • GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
  • GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
  • GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
  • GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
  • GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
  • GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
  • GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
  • GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
  • GO-2026-5969 GHSA-g936-7jqj-mwv8
  • GO-2026-5970 CVE-2026-56852
  • GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
  • GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
  • GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
  • GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
  • GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
  • GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
  • GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
  • GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
  • GO-2026-5981 GHSA-mqxv-9rm6-w8qc
  • GO-2026-5982 GHSA-pqg7-v6wh-3pfp
  • GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
  • GO-2026-5985 GHSA-7rx3-5wx3-5v76
  • GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
  • GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
  • GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
  • GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
  • GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
  • GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
  • GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
  • GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
  • GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
  • GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
  • GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
  • GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
  • GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
  • GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
  • GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
  • GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
Record
openSUSE-SU-2026:21483-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/opencost/opencost
Go
 before 1.119.1
1.119.1
govulncheck-vulndb
openSUSE:Leap 16.0
From an advisory covering 1734 CVEs
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-44300 is a high vulnerability (CVSS 8.8) in Opencost, published July 14, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.75%, the 55th percentile. Fixed in github.com/opencost/opencost 1.119.1.

References

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