CVE-2026-28737

Gitea versions from 1.25.0 before 1.26.0 allow stored cross-site scripting through the extensionsRequired field in glTF files rendered by the 3D file viewer.

Gitea versions from 1.25.0 before 1.26.0 allow stored cross-site scripting through the extensionsRequired field in glTF files rendered by the 3D file viewer.

Summary

Me again.

Gitea's built-in 3D file viewer (powered by Online3DViewer) is vulnerable to stored cross-site scripting (XSS) through crafted .gltf files. When a glTF file declares an unsupported required extension, Online3DViewer generates an error message containing the extension name and Gitea inserts it into the DOM using innerHTML without sanitization. An attacker who can push a .gltf file to any repository can execute arbitrary JavaScript in the context of any user who views the file.

Affected Versions

• Gitea 1.25.0 and later (3D file preview was introduced in 1.25 via the Online3DViewer integration)
• Confirmed on gitea:1.25-nightly (SHA e33d1da...), which bundles online-3d-viewer npm package v0.16.0
• The upstream Online3DViewer library is the root cause

Severity

• Stored XSS: the payload persists in the repository and fires on every page view
• Executes under the Gitea origin with the victim's session (cookies, CSRF tokens)
• Any authenticated user viewing the file is compromised
• Enables full account takeover (token creation, settings modification, repository manipulation)
• No user interaction beyond viewing the file page is required

Details

Root Cause

When Online3DViewer parses a glTF file, it checks whether all extensionsRequired entries are supported. For unsupported extensions, it calls:

// In the Online3DViewer bundle (online-3d-viewer.js)
// Approximate offset 1142618 in the bundled chunk
this.SetError(yp("Unsupported extension: {0}.", unsupportedExtensions.join(", ")));

The SetError method stores this message, and Gitea's rendering code inserts it into the page using innerHTML:

// Gitea's error display handler
element.innerHTML = errorMessage;  // unsanitized

The extension names from extensionsRequired are taken directly from the JSON file with no escaping or sanitization, allowing HTML injection.

Attack Vector

1. An attacker creates a .gltf file with a malicious extensionsRequired value:

{
  "asset": {"version": "2.0"},
  "buffers": [],
  "extensionsRequired": ["<img src=x onerror=\"alert(document.cookie)\">"],
  "scenes": []
}

2. The attacker pushes this file to any Gitea repository they have write access to (including forks of public repositories).

3. When any user navigates to the file's page in the Gitea web UI, the 3D viewer attempts to render it, encounters the "unsupported extension," and inserts the error message (containing the attacker's HTML) into the DOM via innerHTML.

4. The injected <img onerror> handler executes arbitrary JavaScript under the Gitea origin with the victim's authenticated session.

Impact

From the XSS context, an attacker can:

• Create API access tokens for the victim by POSTing to /user/settings/applications with the page's CSRF token
• Read private repositories via same-origin API calls
• Modify repository contents (supply chain attacks)
• Escalate to admin if the victim is a Gitea administrator
• Exfiltrate data via fetch, XMLHttpRequest, or navigator.sendBeacon

Proof of Concept

Minimal PoC (alert box)

Save as poc.gltf and push to any Gitea 1.25+ repository:

{
  "asset": {"version": "2.0"},
  "buffers": [],
  "extensionsRequired": ["<img src=x onerror=\"alert('XSS: '+document.domain)\">"],
  "scenes": []
}

Navigate to the file in the Gitea web UI. The alert will fire.

Suggested Fixes

Sanitize or text-encode the error message before DOM insertion. Replace innerHTML with textContent for error display:

// Instead of:
element.innerHTML = errorMessage;

// Use:
element.textContent = errorMessage;

Alternatively, escape HTML entities in the error message before insertion.

Additional hardening

• Render 3D file previews inside a sandboxed <iframe> with sandbox="allow-scripts" and a restrictive CSP (`default-src…

Gitea versions from 1.25.0 before 1.26.0 allow stored cross-site scripting through the extensionsRequired field in glTF files rendered by the 3D file viewer.

Gitea versions from 1.25.0 before 1.26.0 allow stored cross-site scripting through the extensionsRequired field in glTF files rendered by the 3D file viewer.

Summary

Me again.

Gitea's built-in 3D file viewer (powered by Online3DViewer) is vulnerable to stored cross-site scripting (XSS) through crafted .gltf files. When a glTF file declares an unsupported required extension, Online3DViewer generates an error message containing the extension name and Gitea inserts it into the DOM using innerHTML without sanitization. An attacker who can push a .gltf file to any repository can execute arbitrary JavaScript in the context of any user who views the file.

Affected Versions

• Gitea 1.25.0 and later (3D file preview was introduced in 1.25 via the Online3DViewer integration)
• Confirmed on gitea:1.25-nightly (SHA e33d1da...), which bundles online-3d-viewer npm package v0.16.0
• The upstream Online3DViewer library is the root cause

Severity

• Stored XSS: the payload persists in the repository and fires on every page view
• Executes under the Gitea origin with the victim's session (cookies, CSRF tokens)
• Any authenticated user viewing the file is compromised
• Enables full account takeover (token creation, settings modification, repository manipulation)
• No user interaction beyond viewing the file page is required

Details

Root Cause

When Online3DViewer parses a glTF file, it checks whether all extensionsRequired entries are supported. For unsupported extensions, it calls:

// In the Online3DViewer bundle (online-3d-viewer.js)
// Approximate offset 1142618 in the bundled chunk
this.SetError(yp("Unsupported extension: {0}.", unsupportedExtensions.join(", ")));

The SetError method stores this message, and Gitea's rendering code inserts it into the page using innerHTML:

// Gitea's error display handler
element.innerHTML = errorMessage;  // unsanitized

The extension names from extensionsRequired are taken directly from the JSON file with no escaping or sanitization, allowing HTML injection.

Attack Vector

1. An attacker creates a .gltf file with a malicious extensionsRequired value:

{
  "asset": {"version": "2.0"},
  "buffers": [],
  "extensionsRequired": ["<img src=x onerror=\"alert(document.cookie)\">"],
  "scenes": []
}

2. The attacker pushes this file to any Gitea repository they have write access to (including forks of public repositories).

3. When any user navigates to the file's page in the Gitea web UI, the 3D viewer attempts to render it, encounters the "unsupported extension," and inserts the error message (containing the attacker's HTML) into the DOM via innerHTML.

4. The injected <img onerror> handler executes arbitrary JavaScript under the Gitea origin with the victim's authenticated session.

Impact

From the XSS context, an attacker can:

• Create API access tokens for the victim by POSTing to /user/settings/applications with the page's CSRF token
• Read private repositories via same-origin API calls
• Modify repository contents (supply chain attacks)
• Escalate to admin if the victim is a Gitea administrator
• Exfiltrate data via fetch, XMLHttpRequest, or navigator.sendBeacon

Proof of Concept

Minimal PoC (alert box)

Save as poc.gltf and push to any Gitea 1.25+ repository:

{
  "asset": {"version": "2.0"},
  "buffers": [],
  "extensionsRequired": ["<img src=x onerror=\"alert('XSS: '+document.domain)\">"],
  "scenes": []
}

Navigate to the file in the Gitea web UI. The alert will fire.

Suggested Fixes

Sanitize or text-encode the error message before DOM insertion. Replace innerHTML with textContent for error display:

// Instead of:
element.innerHTML = errorMessage;

// Use:
element.textContent = errorMessage;

Alternatively, escape HTML entities in the error message before insertion.

Additional hardening

• Render 3D file previews inside a sandboxed <iframe> with sandbox="allow-scripts" and a restrictive CSP (`default-src…

Gitea: Stored XSS via glTF extensionsRequired in Gitea 3D File Viewer in code.gitea.io/gitea

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 *…