Gitea fork synchronization can expose private parent repository data

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Gitea 1.26.2 allows fork synchronization to continue after a parent repository changes from public to private, exposing data to a fork that should no longer be authorized.

Source published

3 Jul 2026 20:19:31 UTC

Source modified

7 Jul 2026 17:00:21 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

Gitea 1.26.2 allows fork synchronization to continue after a parent repository changes from public to private, exposing data to a fork that should no longer be authorized.

Source published

Jul 3, 2026, 8:19:31 PM (timezone not stated)

Source modified

Jul 7, 2026, 5:00:21 PM (timezone not stated)

Observed here

7 Nov 2026 06:38:31 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Gitea 1.26.2 allows fork synchronization to continue after a parent repository changes from public to private, exposing data to a fork that should no longer be authorized.

Source published

3 Jul 2026 21:16:57 UTC

Source modified

25 Oct 2026 15:10:00 UTC

Observed here

27 Oct 2026 06:23:40 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 134c704f-9b21-4f2e-91b3-4a467353bcc0 · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

### Summary The `POST /api/v1/repos/{owner}/{repo}/merge-upstream` endpoint continues to synchronize commits from a parent repository after the parent repository has been changed from public to private. A fork created while the parent repository was public can still receive commits made after the parent repository becomes private. As a result, content added during the private period becomes available through the fork repository after synchronization. ### Details Gitea provides the `merge-upstream` API to synchronize a fork with its parent repository. A typical workflow is: 1. A repository is public. 2. Another user creates a fork. 3. The fork owner uses `merge-upstream` to receive updates from the parent repository. However, if the parent repository is later changed from public to private, the synchronization endpoint continues to import new commits from the parent repository into the fork. In testing on Gitea 1.26.2, a fork owner who can no longer directly access the parent repository is still able to synchronize newly created commits from the parent repository into the fork by calling `merge-upstream`. As a result, commits created after the visibility change can be propagated into the fork through the normal fork synchronization workflow. ### PoC #### Proof-of-Concept Code https://anonymous.4open.science/r/Gitea_PoC-EC93/4_poc_merge_upstream #### PoC Details 1. User `alice` creates a public repository `alice/P`. 2. User `bob` forks the repository, creating `bob/P`. 3. `alice` changes `alice/P` from public to private. 4. Verify that `bob` can no longer directly access the parent repository: ```http GET /api/v1/repos/alice/P ``` Response: ```http 404 Not Found ``` ```http GET /api/v1/repos/alice/P/contents/README.md ``` Response: ```http 404 Not Found ``` 5. While the repository is private, `alice` commits a new file: ```text secret.txt ``` 6. Verify that `bob` cannot directly access the new file from the parent repository: ```http GET /api/v1/repos/alice/P/contents/secret.txt ``` Response: ```http 404 Not Found ``` 7. `bob` synchronizes the fork: ```http POST /api/v1/repos/bob/P/merge-upstream ``` Response: ```http 200 OK ``` 8. The newly added file is now available through the fork repository: ```http GET /api/v1/repos/bob/P/contents/secret.txt ``` Response: ```http 200 OK ``` The attached PoC reproduces the behavior end-to-end. As a control test, attempting to access the private-period commit directly through the fork's Git API before synchronization fails: ```http GET /api/v1/repos/bob/P/git/commits/<private-period-commit-sha> ``` Response: ```http 404 Not Found ``` This indicates that the commit becomes available in the fork only after the `merge-upstream` operation synchronizes it from the parent repository. ### Impact A fork created while a repository is public can continue receiving updates from the parent repository after the parent repository is changed to private. Consequently, content committed after the visibility change may become available through fork synchronization even when the fork owner can no longer directly access the parent repository. The impact is limited to content that is synchronized from the parent repository into the affected fork. The issue does not allow modification of the parent repository or access to repositories that were never forked.

Source published

21 Jul 2026 21:42:28 UTC

Source modified

27 Jul 2026 17:11:40 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

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

Publisher rating · HIGH

Gitea: Fork Synchronization Continues After Parent Repository Changes from Public to Private in code.gitea.io/gitea

Source published

27 Jul 2026 15:32:45 UTC

Source modified

27 Jul 2026 17:00:26 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.