GHSA-66m4-5jjr-2rg5 CVE-2026-58440 GO-2026-6033

Gitea: Webhooks created by a collaborator keep firing after their repo access is revoked → ongoing real-time exfiltration of private repo content

Medium Go

Severity: 6.8 / 10; Medium · CVSS 3.1
Exploit chance (EPSS): 0.48%; Chance of exploitation in the next 30 days. Higher than 41.68% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-863 Incorrect Authorization
Fix: 1.27.0; Upgrade gitea.dev to this version or later

Description

Affected product

Gitea — services/repository/collaboration.go (DeleteCollaboration) + webhook delivery

Summary

When a collaborator with admin permission on a private repo creates a webhook, that webhook keeps firing after the collaborator's access is revoked. Gitea's revocation cleanup DeleteCollaboration removes the collaboration record, recalculates accesses, drops watches, and unassigns issues — but it does not remove or disable webhooks the user created, and webhook delivery never re-checks whether the creator still has repo access. The former collaborator therefore receives the full payload (issue/comment bodies, commit data) of all future repository events at their controlled endpoint, indefinitely and invisibly.

Affected code

services/repository/collaboration.go → DeleteCollaboration() — cleans watches/assignees only; no webhook cleanup.
Webhook delivery path — fires on repo events without re-validating the creator's current access.

Steps to reproduce

Using the provided reproduction materials:

Attacker (admin collaborator) creates a webhook → revoke access.
Control: GET /api/v1/repos/admin/wh-repo (attacker) → 404.
GET .../hooks → webhook still active=true.
Admin creates a new issue after revocation → the catcher receives action:"opened", issue.title:"CRITICAL SECRET: …", issue.body (sentinel private key), repository.private:true. (Runtime-confirmed on gitea/gitea:1.25.4. Catcher is an internal sentinel listener; the payload is a planted sentinel, not real data; nothing is sent to any external/metadata endpoint.)

Impact

Authenticated former admin-collaborator → ongoing real-time exfiltration of private content created after revocation; invisible to the owner; scope crosses from the application boundary to data the user should no longer access.

Suggested remediation

On revocation, delete/disable webhooks created by the removed collaborator (or hand them to the owner).
Re-validate the creator's current repo access before each webhook delivery.
At minimum, warn admins on revocation if the user created webhooks.

Credit

Reported as part of an incomplete-patch / authorization-residue measurement study (responsible disclosure).

Affected versions

Go

Package	Vulnerable	Fixed in
gitea.dev	`< 1.27.0`	`1.27.0`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

gitea.dev Go → `1.27.0`

go

go get gitea.dev@v1.27.0 && go mod tidy

Severity breakdown

CVSS 3.1 6.8

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

Attack vector: Network
Attack complexity: Low
Privileges required: High
User interaction: None
Scope: Changed
Confidentiality: High
Integrity: None
Availability: None

Weakness

CWE-863: Incorrect Authorization

The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.

How to prevent it

Architecture and Design: Divide the product into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully mapping roles with data and functionality. Use role-based access control (RBAC) [REF-229] to enforce the roles at the appropriate boundaries. Note that this approach may not protect against horizontal authorization, i.e., it will not protect a user from attacking others with the same role.
Architecture and Design: Ensure that access control checks are performed related to the business logic. These checks may be different than the access control checks that are applied to more generic resources such as files, connections, processes, memory, and database records. For example, a database may restrict access for medical records to a specific database user, but each record might only be intended to be accessible to the patient and the patient's doctor [REF-7].
Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, consider using authorization frameworks such as the JAAS Authorization Framework [REF-233] and the OWASP ESAPI Access Control feature [REF-45].
Architecture and Design: For web applications, make sure that the access control mechanism is enforced correctly at the server side on every page. Users should not be able to access any unauthorized functionality or information by simply requesting direct access to that page. One way to do this is to ensure that all pages containing sensitive information are not cached, and that all such pages restrict access to requests that are accompanied by an active and authenticated session token associated with a user who has the required permissions to access that page.
System Configuration, Installation: Use the access control capabilities of your operating system and server environment and define your access control lists accordingly. Use a "default deny" policy when defining these ACLs.

References

Packages

github.com/go-gitea/gitea

Timeline

Jul 21, 2026 Published
Aug 26, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-rcr6-4jqh-j84m Gitea: Remote Code Execution via diffpatch Git Hook Installation	Critical Known exploited	Also affects gitea.dev
GHSA-fq2p-5p22-8g6j Gitea: Public-Only Personal access tokens scope bypass in Organization and Permission Endpoints	Medium	Also affects gitea.dev
GHSA-2wm4-vwp6-v7xc Gitea: SSRF via Migration Asset Downloads Bypasses hostmatcher — Reads Internal Files and Cloud Metadata	High	Also affects gitea.dev
GHSA-3r5c-2xxx-h872 Gitea: Webhook Authorization Header Returned in Plaintext via API	Low	Also affects gitea.dev
GHSA-frpw-3h2q-4jj6 Gitea: Cross-Repo Information Disclosure via Org-Level Actions Run/Job APIs	Medium	Also affects gitea.dev
GHSA-q423-49rw-g9mh Gitea: GHSA-8fwc-qjw5-rvgp ClearRepoWatches fix not applied to API EditRepo path — sister code path retains stale watches on public->private	Medium	Also affects gitea.dev
GHSA-h56g-4qw7-2mxg Gitea: Public-only API token restriction is not enforced on team API routes	Medium	Also affects gitea.dev
GHSA-prr9-9mp4-5gp2 Gitea: Private org member list leaked via /members API endpoint — incomplete fix for PR #38145	High	Also affects gitea.dev

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