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CVE-2026-42880

ArgoCD ServerSideDiff is vulnerable to Kubernetes Secret Extraction

9.6 CriticalPublic exploitFix available

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. From versions 3.2.0 to before 3.2.11 and 3.3.0 to before 3.3.9, there is a missing authorization and data-masking gap in Argo CD's ServerSideDiff endpoint that allows an attacker with read-only access to extract plaintext Kubernetes Secret data from etcd via the Kubernetes API server's Server-Side Apply dry-run mechanism. This issue has been patched in versions 3.2.11 and 3.3.9.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
Low
User interaction
None

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
None

Exploit likelihood

0.65%Up 0.6 points since May 8, 2026
90%50%10%1%

What each source reports

CVE List Score used 9.6

ArgoCD ServerSideDiff is vulnerable to Kubernetes Secret Extraction

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. From versions 3.2.0 to before 3.2.11 and 3.3.0 to before 3.3.9, there is a missing authorization and data-masking gap in Argo CD's ServerSideDiff endpoint that allows an attacker with read-only access to extract plaintext Kubernetes Secret data from etcd via the Kubernetes API server's Server-Side Apply dry-run mechanism. This issue has been patched in versions 3.2.11 and 3.3.9.

Record
CVE-2026-42880
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
CVSS 3.1
7.7 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-200, CWE-212, CWE-201
Updated
2026-11-02
EUVDEUVD-2026-28469 9.6

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. From versions 3.2.0 to before 3.2.11 and 3.3.0 to before 3.3.9, there is a missing authorization and data-masking gap in Argo CD's ServerSideDiff endpoint that allows an attacker with read-only access to extract plaintext Kubernetes Secret data from etcd via the Kubernetes API server's Server-Side Apply dry-run mechanism. This issue has been patched in versions 3.2.11 and 3.3.9.

Record
EUVD-2026-28469
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-3v3m-wc6v-x4x3 9.6

ArgoCD ServerSideDiff is vulnerable to Kubernetes Secret Extraction

Summary

There is a missing authorization and data-masking gap in Argo CD's ServerSideDiff endpoint that allows an attacker with read-only access to extract plaintext Kubernetes Secret data from etcd via the Kubernetes API server's Server-Side Apply dry-run mechanism.

Details

Argo CD masks Secret data in every endpoint that returns Kubernetes resource state except one. All the other endpoints such as GetManifests, GetManifestsWithFiles, GetResource and PatchResource utilize hideSecretData() to mask the returned secret value. The vulnerable function ServerSideDiff gRPC/REST endpoint (/application.ApplicationService/ServerSideDiff) constructs its response with raw, unmasked PredictedLive and NormalizedLive states:

// server/application/application.go:3051-3062
responseDiffs = append(responseDiffs, &v1alpha1.ResourceDiff{
    TargetState:     string(diffRes.PredictedLive),
    LiveState:       string(diffRes.NormalizedLive),
})

A user only requires RBAC to call this ServerSideDiff function. Every authenticated Argo CD user has get access via the default role:catch-all policy. However, Argo CD has a defense layer called removeWebhookMutation() that normally strips non-Argo CD-managed fields from the Server Side Apply (SSA) dry-run response and merges them with the client-provided (masked) live state. This prevents real Secret values from leaking through the diff. However, this defense is entirely skipped when the Application has the annotation argocd.argoproj.io/compare-options: IncludeMutationWebhook=true. When IncludeMutationWebhook=true is set, ignoreMutationWebhook becomes false, and the defense is skipped entirely:

if o.ignoreMutationWebhook {
    predictedLive, err = removeWebhookMutation(predictedLive, live, o.gvkParser, o.manager)
}

The raw Kubernetes SSA dry-run response which contains real Secret values read from etcd is then flown directly into the API response with no masking.

When ServerSideDiff is called, the handler invokes K8sServerSideDryRunner.Run(), which performs the equivalent of:

kubectl apply --server-side --dry-run=server --field-manager=argocd-controller For extraction to succeed, the Secret's data fields must be owned by at least one non-Argo CD SSA field manager. When argocd-controller is the sole field manager for data, the SSA dry-run garbage-collects those fields (since the target manifest omits them). When a second manager exists (e.g., kube-controller-manager), that manager retains ownership and the real values survive in the response.

PoC

#!/usr/bin/env python3
"""
Argo CD ServerSideDiff Secret Extraction PoC

Usage:
    python3 poc.py <host> <token> <app> <project>

Example:
    python3 poc.py argocd.int.<customer>.com eyJhbG... my-app my-project
"""

import base64
import http.client
import json
import ssl
import struct
import sys
import urllib.parse
from collections import defaultdict

def encode_varint(v):
    out = []
    while v > 0x7f:
        out.append((v & 0x7f) | 0x80)
        v >>= 7
    out.append(v & 0x7f)
    return bytes(out)

def encode_str(field, val):
    tag = (field << 3) | 2
    raw = val.encode()
    return encode_varint(tag) + encode_varint(len(raw)) + raw

def encode_bytes(field, val):
    tag = (field << 3) | 2
    return encode_varint(tag) + encode_varint(len(val)) + val

def encode_bool(field, val):
    tag = (field << 3) | 0
    return encode_varint(tag) + encode_varint(1 if val else 0)

def decode_varint(data, pos):
    val, shift = 0, 0
    while pos < len(data):
        b = data[pos]; pos += 1
        val |= (b & 0x7f) << shift; shift += 7
        if not (b & 0x80):
            break
    return val, pos

def decode_fields(data):
    fields = defaultdict(list)
    pos = 0
    while pos < len(data):
        tag, pos = decode_varint(data, pos)
        wtype = tag & 0x07
        if wtype == 0:
            val, pos = decode_varint(data, pos)
            fields[tag >> 3].append(val)
        elif wtype == 2:
            length, pos…
Record
GHSA-3v3m-wc6v-x4x3
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
Weakness
CWE-200, CWE-212
Updated
2026-11-02
NVD 9.6

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. From versions 3.2.0 to before 3.2.11 and 3.3.0 to before 3.3.9, there is a missing authorization and data-masking gap in Argo CD's ServerSideDiff endpoint that allows an attacker with read-only access to extract plaintext Kubernetes Secret data from etcd via the Kubernetes API server's Server-Side Apply dry-run mechanism. This issue has been patched in versions 3.2.11 and 3.3.9.

Record
CVE-2026-42880
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
CVSS 3.1
7.7 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-200, CWE-212, CWE-201
Updated
2026-11-02
OSV 9.6

ArgoCD ServerSideDiff is vulnerable to Kubernetes Secret Extraction

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. From versions 3.2.0 to before 3.2.11 and 3.3.0 to before 3.3.9, there is a missing authorization and data-masking gap in Argo CD's ServerSideDiff endpoint that allows an attacker with read-only access to extract plaintext Kubernetes Secret data from etcd via the Kubernetes API server's Server-Side Apply dry-run mechanism. This issue has been patched in versions 3.2.11 and 3.3.9.

Record
CVE-2026-42880
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
Weakness
CWE-200, CWE-212
Updated
2026-11-02
OSVCVE-2026-43824 7.7

In Argo CD 3.2.0 before 3.2.11 and 3.3.0 before 3.3.9, ServerSideDiff allows reading cleartext Kubernetes Secret data.

Record
CVE-2026-43824
CVSS 3.1
7.7 HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N
Weakness
CWE-212
Updated
2026-11-02
Show 4 moreShow less
OSVGHSA-3v3m-wc6v-x4x3 9.6

ArgoCD ServerSideDiff is vulnerable to Kubernetes Secret Extraction

Summary

There is a missing authorization and data-masking gap in Argo CD's ServerSideDiff endpoint that allows an attacker with read-only access to extract plaintext Kubernetes Secret data from etcd via the Kubernetes API server's Server-Side Apply dry-run mechanism.

Details

Argo CD masks Secret data in every endpoint that returns Kubernetes resource state except one. All the other endpoints such as GetManifests, GetManifestsWithFiles, GetResource and PatchResource utilize hideSecretData() to mask the returned secret value. The vulnerable function ServerSideDiff gRPC/REST endpoint (/application.ApplicationService/ServerSideDiff) constructs its response with raw, unmasked PredictedLive and NormalizedLive states:

// server/application/application.go:3051-3062
responseDiffs = append(responseDiffs, &v1alpha1.ResourceDiff{
    TargetState:     string(diffRes.PredictedLive),
    LiveState:       string(diffRes.NormalizedLive),
})

A user only requires RBAC to call this ServerSideDiff function. Every authenticated Argo CD user has get access via the default role:catch-all policy. However, Argo CD has a defense layer called removeWebhookMutation() that normally strips non-Argo CD-managed fields from the Server Side Apply (SSA) dry-run response and merges them with the client-provided (masked) live state. This prevents real Secret values from leaking through the diff. However, this defense is entirely skipped when the Application has the annotation argocd.argoproj.io/compare-options: IncludeMutationWebhook=true. When IncludeMutationWebhook=true is set, ignoreMutationWebhook becomes false, and the defense is skipped entirely:

if o.ignoreMutationWebhook {
    predictedLive, err = removeWebhookMutation(predictedLive, live, o.gvkParser, o.manager)
}

The raw Kubernetes SSA dry-run response which contains real Secret values read from etcd is then flown directly into the API response with no masking.

When ServerSideDiff is called, the handler invokes K8sServerSideDryRunner.Run(), which performs the equivalent of:

kubectl apply --server-side --dry-run=server --field-manager=argocd-controller For extraction to succeed, the Secret's data fields must be owned by at least one non-Argo CD SSA field manager. When argocd-controller is the sole field manager for data, the SSA dry-run garbage-collects those fields (since the target manifest omits them). When a second manager exists (e.g., kube-controller-manager), that manager retains ownership and the real values survive in the response.

PoC

#!/usr/bin/env python3
"""
Argo CD ServerSideDiff Secret Extraction PoC

Usage:
    python3 poc.py <host> <token> <app> <project>

Example:
    python3 poc.py argocd.int.<customer>.com eyJhbG... my-app my-project
"""

import base64
import http.client
import json
import ssl
import struct
import sys
import urllib.parse
from collections import defaultdict

def encode_varint(v):
    out = []
    while v > 0x7f:
        out.append((v & 0x7f) | 0x80)
        v >>= 7
    out.append(v & 0x7f)
    return bytes(out)

def encode_str(field, val):
    tag = (field << 3) | 2
    raw = val.encode()
    return encode_varint(tag) + encode_varint(len(raw)) + raw

def encode_bytes(field, val):
    tag = (field << 3) | 2
    return encode_varint(tag) + encode_varint(len(val)) + val

def encode_bool(field, val):
    tag = (field << 3) | 0
    return encode_varint(tag) + encode_varint(1 if val else 0)

def decode_varint(data, pos):
    val, shift = 0, 0
    while pos < len(data):
        b = data[pos]; pos += 1
        val |= (b & 0x7f) << shift; shift += 7
        if not (b & 0x80):
            break
    return val, pos

def decode_fields(data):
    fields = defaultdict(list)
    pos = 0
    while pos < len(data):
        tag, pos = decode_varint(data, pos)
        wtype = tag & 0x07
        if wtype == 0:
            val, pos = decode_varint(data, pos)
            fields[tag >> 3].append(val)
        elif wtype == 2:
            length, pos…
Record
GHSA-3v3m-wc6v-x4x3
CVSS 3.1
9.6 CriticalCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N
Weakness
CWE-200, CWE-212
Updated
2026-11-02
OSVBIT-argo-cd-2026-42880 No score

ArgoCD ServerSideDiff is vulnerable to Kubernetes Secret Extraction

Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes. From versions 3.2.0 to before 3.2.11 and 3.3.0 to before 3.3.9, there is a missing authorization and data-masking gap in Argo CD's ServerSideDiff endpoint that allows an attacker with read-only access to extract plaintext Kubernetes Secret data from etcd via the Kubernetes API server's Server-Side Apply dry-run mechanism. This issue has been patched in versions 3.2.11 and 3.3.9.

Record
BIT-argo-cd-2026-42880
Updated
2026-11-02
OSVGO-2026-5099 No score

ArgoCD ServerSideDiff is vulnerable to Kubernetes Secret Extraction in github.com/argoproj/argo-cd

ArgoCD ServerSideDiff is vulnerable to Kubernetes Secret Extraction in github.com/argoproj/argo-cd

Record
GO-2026-5099
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/argoproj/argo-cd/v3
Go
 3.2.0 up to 3.2.11
3.2.11
github.com/argoproj/argo-cd/v3
Go
 3.3.0 up to 3.3.9
3.3.9
argo-cd
Bitnami
From an advisory covering 2 CVEs
 3.2.0 up to 3.2.11, 3.3.0 up to 3.3.9
3.2.113.3.9
github.com/argoproj/argo-cd/v3
Go
From an advisory covering 2 CVEs
 3.2.0 up to 3.2.11
3.2.11
github.com/argoproj/argo-cd/v3
Go
From an advisory covering 2 CVEs
 3.3.0 up to 3.3.9
3.3.9
github.com/argoproj/argo-cd
Go
From an advisory covering 2 CVEs
 All versions None known
github.com/argoproj/argo-cd/v2
Go
From an advisory covering 2 CVEs
 All versions None known
github.com/argoproj/argo-cd/v3
Go
From an advisory covering 2 CVEs
 3.2.0 up to 3.2.11, 3.3.0 up to 3.3.9
3.2.113.3.9
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

Public exploits

Links only. Every CVE stores no exploit code.

Public exploits
SourceLinkDate
PoC in GitHubHAERIN-L/POC_CVE-2026-428802026-05-25

History

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

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

In short

CVE-2026-42880 is a critical vulnerability (CVSS 9.6) in Argoproj Argo Cd, published May 2, 2026. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 0.65%, the 51st percentile. Fixed in github.com/argoproj/argo-cd/v3 3.2.11.

References

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Left out here: 1,550 references and the rest of 3 source descriptions. The JSON record has them.

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