# CVE-2025-4839: itwanger paicoding CrossUtil.java cross-domain policy

> Attackers can bypass cross-domain restrictions in paicoding due to permissive CORS policies, potentially enabling unauthorized cross-origin requests.

- **Severity:** Low 2.3 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 17 May 2025
- **Updated:** 19 May 2025
- **Also known as:** GHSA-vq5p-c2v7-53v5

## What is CVE-2025-4839?

CVE-2025-4839 is a low-severity vulnerability in itwanger paicoding, published on 17 May 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

A vulnerability has been found in itwanger paicoding 1.0.0/1.0.1/1.0.2/1.0.3 and classified as problematic. Affected by this vulnerability is an unknown functionality of the file /paicoding-core/src/main/java/com/github/paicoding/forum/core/util/CrossUtil.java. The manipulation leads to permissive cross-domain policy with untrusted domains. The attack can be launched remotely. The complexity of an attack is rather high. The exploitation appears to be difficult. The exploit has been disclosed to the public and may be used.

Weakness: CWE-942 (Permissive Cross-domain Security Policy with Untrusted Domains), CWE-346 (Origin Validation Error)

## Which versions are affected by CVE-2025-4839?

It affects 1 product.


Products: Itwanger Paicoding.

## How do I fix CVE-2025-4839?

No fix has been published for CVE-2025-4839 yet. Limit exposure of the affected software until one is available.

## Is CVE-2025-4839 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-4839 exists.

## Other vulnerabilities in itwanger paicoding

- [CVE-2026-3286](https://insights.sbomify.com/CVE-2026-3286/): itwanger paicoding Image Save Endpoint ImageRestController.java save server-side request forgery (medium 5.3)
- [CVE-2025-3966](https://insights.sbomify.com/CVE-2025-3966/): itwanger paicoding Browsing History home information disclosure (medium 5.3)
- [CVE-2025-3967](https://insights.sbomify.com/CVE-2025-3967/): itwanger paicoding Article post improper authorization (medium 5.3)
- [CVE-2025-3965](https://insights.sbomify.com/CVE-2025-3965/): itwanger paicoding post cross site scripting (medium 5.1)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-4839 and fix it if it is affected.

What it is: CVE-2025-4839 is a low-severity vulnerability in itwanger paicoding, published on 17 May 2025. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-4839 exists.

Affected product: itwanger paicoding. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-4839/ (Markdown: https://insights.sbomify.com/CVE-2025-4839/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-4839
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-4839
- OSV: https://osv.dev/vulnerability/CVE-2025-4839

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-4839/
Summaries are generated and may contain mistakes; the official description above is the record.