# CVE-2026-28355: "PWA" Canarytoken Vulnerable to Stored Self Cross-Site Scripting

> Attackers can inject JavaScript into PWA Canarytoken titles, executing code when victims visit the installation page.

- **Severity:** Low 1.3 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:U`)
- **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:** 27 Feb 2026
- **Updated:** 3 Mar 2026

## What is CVE-2026-28355?

CVE-2026-28355 is a low-severity cross-site scripting vulnerability in thinkst canarytokens, published on 27 Feb 2026. 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

Canarytokens help track activity and actions on a network. Versions prior to `sha-7ff0e12` have a Self Cross-Site Scripting vulnerability in the "PWA" Canarytoken, whereby the Canarytoken's creator can attack themselves or someone they share the link with. The creator of a PWA Canarytoken can insert Javascript into the title field of their PWA token. When the creator later browses the installation page for their own Canarytoken, the Javascript executes. This is a self-XSS. An attacker could create a Canarytoken with this self-XSS, and send the install link to a victim. When they click on it, the Javascript would execute. However, no sensitive information (ex. session information) will be disclosed to the malicious actor. This issue is now patched on Canarytokens.org. Users of self-hosted Canarytokens installations can update by pulling the latest Docker image, or any Docker image after sha-7ff0e12.

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

## Which versions are affected by CVE-2026-28355?


## How do I fix CVE-2026-28355?

No fix has been published for CVE-2026-28355 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-28355 being exploited?

There is no known exploitation of CVE-2026-28355 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-28355 and fix it if it is affected.

What it is: CVE-2026-28355 is a low-severity cross-site scripting vulnerability in thinkst canarytokens, published on 27 Feb 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-28355 in the wild and no public exploit code.

Affected product: thinkst canarytokens. 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-2026-28355/ (Markdown: https://insights.sbomify.com/CVE-2026-28355/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-28355
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-28355
- OSV: https://osv.dev/vulnerability/CVE-2026-28355

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-28355/
Summaries are generated and may contain mistakes; the official description above is the record.