Security Digest · Vulnerability record
CVE-2026-42880: ArgoCD ServerSideDiff is vulnerable to Kubernetes Secret Extraction
Argo CD is a declarative, GitOps continuous delivery tool for Kubernetes.
CVSS 9.6 Critical EPSS 0.6% · p46
Should you act?
Critical, preconditions apply
Severe if exploited, but exploitation needs conditions that may not apply to you. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.
- Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 0.6%, percentile 46: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 46% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Needs an account (low (any account)). Exposure depends on who can log in.
- Only applies if your dependency tree includes
github.com/argoproj/argo-cd/v3(Go) >= 3.2.0, < 3.2.11, fixed in 3.2.11;github.com/argoproj/argo-cd/v3(Go) >= 3.3.0, < 3.3.9, fixed in 3.3.9. Check your lockfile, including transitive dependencies.
What it is
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.
From the GitHub advisory
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:
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:
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:
Weakness type: CWE-200, CWE-212, CWE-201.
Product: github.com/argoproj/argo-cd/v3 (Go) · Assigned by: GitHub_M · Published: 2026-05-07
Affected and fixed versions
| Ecosystem | Package | Vulnerable | First fixed |
|---|---|---|---|
| Go | github.com/argoproj/argo-cd/v3 | >= 3.2.0, < 3.2.11 | 3.2.11 |
| Go | github.com/argoproj/argo-cd/v3 | >= 3.3.0, < 3.3.9 | 3.3.9 |
| Vendor | Product | Affected versions (per CVE record) |
|---|---|---|
| argoproj | argo-cd | >= 3.2.0, < 3.2.11, >= 3.3.0, < 3.3.9 |
Severity scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_M | 3.1 | 9.6 Critical | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N |
| redhat-SADP | 3.1 | 7.7 High | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N |
| GitHub | 3.1 | 9.6 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N |
- Attack vector: network (remotely reachable)
- Attack complexity: low
- Privileges required: low (any account)
- User interaction: none
- Scope: changed (can affect other components)
CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.
Exploitation and urgency
- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc, automatable no, technical impact total.
- FIRST EPSS (model of 2026-10-21): 0.56% probability of exploitation activity in the next 30 days; percentile 46.
Timeline
- — CVE record published by GitHub_M
- — GitHub-reviewed advisory GHSA-3v3m-wc6v-x4x3 published (critical)
- — CVE record last updated
Sources and references
Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.
Vendor and project advisories, patches
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
- access.redhat.com access.redhat.com
Vulnerability records
- GitHub Advisory GHSA-3v3m-wc6v-x4x3 github.com
- CVE.org record CVE-2026-42880 cve.org
- NVD entry CVE-2026-42880 nvd.nist.gov
Other references from the CVE record and advisory
- github.com github.com
- access.redhat.com access.redhat.com
- RHBZ#2467882 bugzilla.redhat.com
- security.access.redhat.com security.access.redhat.com