# CVE-2021-41156: Reflected XSS vulnerability

> Attackers can execute malicious JavaScript in logged-in users' browsers via unsanitized input, potentially leading to account takeover.

- **Severity:** Medium 6.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 18 Oct 2021
- **Updated:** 4 Aug 2024

## What is CVE-2021-41156?

CVE-2021-41156 is a medium-severity cross-site scripting vulnerability in anuko timetracker, published on 18 Oct 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

anuko/timetracker is an, open source time tracking system. In affected versions Time Tracker uses browser_today hidden control on a few pages to collect the today's date from user browsers. Because of not checking this parameter for sanity in versions prior to 1.19.30.5601, it was possible to craft an html form with malicious JavaScript, use social engineering to convince logged on users to execute a POST from such form, and have the attacker-supplied JavaScript to be executed in user's browser. This has been patched in version 1.19.30.5600. Upgrade is recommended. If it is not practical, introduce ttValidDbDateFormatDate function as in the latest version and add a call to it within the access checks block.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2021-41156?

It affects 1 product.


Products: Timetracker Project Timetracker.

## How do I fix CVE-2021-41156?

No fix has been published for CVE-2021-41156 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-41156 being exploited?

There is no known exploitation of CVE-2021-41156 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-41156 and fix it if it is affected.

What it is: CVE-2021-41156 is a medium-severity cross-site scripting vulnerability in anuko timetracker, published on 18 Oct 2021. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-41156 in the wild and no public exploit code.

Affected product: anuko timetracker. 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-2021-41156/ (Markdown: https://insights.sbomify.com/CVE-2021-41156/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-41156
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-41156
- OSV: https://osv.dev/vulnerability/CVE-2021-41156

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-41156/
Summaries are generated and may contain mistakes; the official description above is the record.