zot: Bearer authentication maps DELETE to push scope, allowing unauthorized deletion

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zot is a container image and artifact registry based on the Open Container Initiative Distribution Specification. Prior to 2.1.18, the bearer authentication handler in pkg/api/authn.go maps every HTTP method other than GET and HEAD to the push action, so DELETE requests are not checked for the distinct delete permission. Bearer-authenticated requests also bypass the fine-grained DistSpecAuthzHandler path in pkg/api/authz.go, while DeleteManifest and DeleteBlob perform no independent delete-permission check. A remote attacker with a bearer token limited to pull and push actions can therefore delete manifests and blobs within the token's repository scope, making images unavailable and allowing repository history to be altered despite the token lacking delete authorization. This issue is fixed in version 2.1.18.

Source published

18 Sep 2026 16:55:22 UTC

Source modified

23 Sep 2026 19:06:14 UTC

Saved here

23 Oct 2026 15:48:27 UTC

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CVSS 3.1 · 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

zot is a container image and artifact registry based on the Open Container Initiative Distribution Specification. Prior to 2.1.18, the bearer authentication handler in pkg/api/authn.go maps every HTTP method other than GET and HEAD to the push action, so DELETE requests are not checked for the distinct delete permission. Bearer-authenticated requests also bypass the fine-grained DistSpecAuthzHandler path in pkg/api/authz.go, while DeleteManifest and DeleteBlob perform no independent delete-permission check. A remote attacker with a bearer token limited to pull and push actions can therefore delete manifests and blobs within the token's repository scope, making images unavailable and allowing repository history to be altered despite the token lacking delete authorization. This issue is fixed in version 2.1.18.

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Sep 18, 2026, 4:55:22 PM (timezone not stated)

Source modified

Sep 23, 2026, 7:06:14 PM (timezone not stated)

Saved here

11 Nov 2026 15:03:25 UTC

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ENISA EUVD · source terms and attribution apply

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EUVD CVSS 3.1 · 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

zot is a container image and artifact registry based on the Open Container Initiative Distribution Specification. Prior to 2.1.18, the bearer authentication handler in pkg/api/authn.go maps every HTTP method other than GET and HEAD to the push action, so DELETE requests are not checked for the distinct delete permission. Bearer-authenticated requests also bypass the fine-grained DistSpecAuthzHandler path in pkg/api/authz.go, while DeleteManifest and DeleteBlob perform no independent delete-permission check. A remote attacker with a bearer token limited to pull and push actions can therefore delete manifests and blobs within the token's repository scope, making images unavailable and allowing repository history to be altered despite the token lacking delete authorization. This issue is fixed in version 2.1.18.

Source published

18 Sep 2026 17:16:59 UTC

Source modified

30 Sep 2026 17:32:07 UTC

Saved here

25 Oct 2026 14:19:28 UTC

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CVSS 3.1 · [email protected] · Secondary · 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

### Summary A bearer token with only `pull` and `push` scopes can successfully delete manifests and blobs from a zot registry. The bearer authentication handler maps all non-GET/HEAD HTTP methods, including DELETE, to the `"push"` action, and the `DistSpecAuthzHandler` middleware is bypassed entirely for bearer-authenticated requests. This allows any client holding a push-only bearer token to delete arbitrary manifests and blobs within the token's repository scope, in violation of the [Docker Distribution Token Authentication Specification](https://distribution.github.io/distribution/spec/auth/scope/). ### Details The vulnerability exists in two interacting components: **1. Action Mapping Collapse (`pkg/api/authn.go:571–586`)** The bearer authentication handler maps HTTP methods to token scope actions using a binary check: ```go action := "pull" if m := request.Method; m != http.MethodGet && m != http.MethodHead { action = "push" } ``` This collapses DELETE, PUT, PATCH, and POST into a single `"push"` action. The `"delete"` action is never assigned. **2. Authorization Bypass for Bearer Auth (`pkg/api/authz.go:270–275, 318–323`)** When a request is authenticated via bearer token, the `DistSpecAuthzHandler` middleware, which performs fine-grained action inference (distinguishing `create`, `read`, `update`, and `delete`) is bypassed entirely: ```go if err != nil || (authnMwCtx != nil && authnMwCtx.AuthnType == BEARER) { next.ServeHTTP(response, request) return } ``` **3. No Handler-Level Authorization Check** Neither `DeleteManifest` (`routes.go:799–884`) nor `DeleteBlob` (`routes.go:1192–1241`) performs an independent authorization check for delete permission before executing the deletion. **Deviation from Specification and Reference Implementation** The [[Docker Distribution Token Scope Documentation](https://distribution.github.io/distribution/spec/auth/scope/)](https://distribution.github.io/distribution/spec/auth/scope/) defines `delete` as a distinct action separate from `push`. The reference implementation ([[distribution/distribution](https://github.com/distribution/distribution/blob/main/registry/handlers/app.go)](https://github.com/distribution/distribution/blob/main/registry/handlers/app.go)) correctly maps DELETE requests to the `"delete"` action: ```go case http.MethodDelete: records = append(records, auth.Access{ Resource: resource, Action: "delete", }) ``` Furthermore, zot's own native access-control configuration explicitly distinguishes `delete` as a separate permission from `create` and `update`, confirming the project's intent that delete is a distinct authorization action. **Suggested Fix** In `pkg/api/authn.go`, the action mapping should distinguish DELETE: ```go action := "pull" switch { case m == http.MethodGet || m == http.MethodHead: action = "pull" case m == http.MethodDelete: action = "delete" default: action = "push" } ``` The `DistSpecAuthzHandler` bypass for bearer-authenticated requests (`authz.go:270–275`) should also be reconsidered to ensure bearer-authenticated requests receive equivalently granular authorization checks. ### PoC **Prerequisites:** zot v2.1.15 with bearer authentication enabled, and a token server issuing JWTs with `actions: ["pull", "push"]` (no `"delete"`). **Steps to Reproduce:** 1. Configure zot with bearer authentication pointing to a token server 2. Obtain a bearer token with scope `repository:poc-test:pull,push` (no delete) 3. Upload a config blob: ```bash curl -H "Authorization: Bearer $TOKEN" \ -H "Content-Type: application/octet-stream" \ -X POST "http://127.0.0.1:5001/v2/poc-test/blobs/uploads/?digest=sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a" \ -d '{}' # → 201 Created ``` 4. Push a manifest tagged `v1.0` (succeeds token has push): ```bash curl -H "Authorization: Bearer $TOKEN" \ -H "Content-Type: application/vnd.oci.image.manifest.v1+json" \ -X PUT "http://127.0.0.1:5001/v2/poc-test/manifests/v1.0" \ -d '{"schemaVersion":2,"mediaType":"application/vnd.oci.image.manifest.v1+json","config":{"mediaType":"application/vnd.oci.image.config.v1+json","digest":"sha256:44136fa355b3678a1146ad16f7e8649e94fb4fc21fe77e8310c060f61caaff8a","size":2},"layers":[]}' # → 201 Created ``` 5. DELETE the manifest with the same push-only token (**should return 401, but returns 202**): ```bash curl -H "Authorization: Bearer $TOKEN" \ -X DELETE "http://127.0.0.1:5001/v2/poc-test/manifests/v1.0" # → 202 Accepted (VULNERABLE) ``` 6. Confirm the manifest is gone: ```bash curl -o /dev/null -w "%{http_code}" -H "Authorization: Bearer $TOKEN" \ "http://127.0.0.1:5001/v2/poc-test/manifests/v1.0" # → 404 Not Found ``` **Expected behavior:** Step 5 should return `401 Unauthorized` with a `WWW-Authenticate` header requesting `scope="repository:poc-test:delete"`. **Actual behavior:** Step 5 returns `202 Accepted` and the manifest is permanently deleted. A complete reproducer (minimal Go token server + zot config + automated script) is available upon request. ### Impact **Privilege Escalation / Unauthorized Deletion** Any bearer token with push scope can delete manifests and blobs, even when the token was explicitly issued without delete permissions. This is particularly impactful in CI/CD environments where automated systems are issued least-privilege tokens with only pull and push permissions. A compromised or stolen CI token which should only be able to build and push images can be used to: - Delete arbitrary manifests (tags) within any repository covered by the token's scope - Delete arbitrary blobs within those repositories - Render production container images unpullable - Rewrite image history by removing specific tags

Source published

18 Sep 2026 17:15:19 UTC

Source modified

28 Sep 2026 17:10:49 UTC

Saved here

24 Oct 2026 13:19:41 UTC

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GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Publisher rating · HIGH

zot: Bearer authentication maps DELETE to push scope, allowing unauthorized deletion in zotregistry.dev/zot

Source published

28 Sep 2026 16:43:40 UTC

Source modified

28 Sep 2026 17:00:17 UTC

Saved here

24 Oct 2026 13:19:41 UTC

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OSV · upstream source license applies

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