# CVE-2026-19902: Ad Inserter <= 2.8.18 - Reflected Cross-Site Scripting via {search-query} Dynamic Tag (Referer Header)

> Attackers can execute arbitrary JavaScript in victim browsers via the Referer header if the search-query tag is used, potentially compromising admin accounts.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A: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:** 1 Oct 2026
- **Updated:** 3 Oct 2026
- **Also known as:** GHSA-298r-885r-pj27

## What is CVE-2026-19902?

CVE-2026-19902 is a medium-severity cross-site scripting vulnerability in spacetime Ad Inserter – Ad Manager & AdSense Ads, published on 1 Oct 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

The Ad Inserter – Ad Manager & AdSense Ads plugin for WordPress is vulnerable to Reflected Cross-Site Scripting via the Referer header in all versions up to, and including, 2.8.18 due to insufficient input sanitization and output escaping on the '{search-query}' dynamic tag. When an ad block's code contains that tag, replace_ai_tags() reads $_SERVER['HTTP_REFERER'] and tests it with the regex /[\.\/](google|yahoo|bing|ask)\.[a-z\.]{2,5}[\/]/i. The leading [\.\/] class matches a literal slash, so any referrer merely containing a segment such as '/google.com/' passes as a search-engine referral; the plugin then percent-decodes the referring query with parse_str() and substitutes the resulting 'q' (or 'p') value into the block via preg_replace() with no escaping. This makes it possible for unauthenticated attackers to execute arbitrary JavaScript in the context of the site for any visitor, including a signed-in administrator, by luring them to an attacker-controlled page that frames or links to any ordinary post. Exploitation requires the site to have an ad block whose code uses the '{search-query}' tag with automatic insertion enabled — a documented plugin feature used as intended.

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

## Which versions are affected by CVE-2026-19902?


## How do I fix CVE-2026-19902?

No fix has been published for CVE-2026-19902 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-19902 being exploited?

There is no known exploitation of CVE-2026-19902 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-19902 and fix it if it is affected.

What it is: CVE-2026-19902 is a medium-severity cross-site scripting vulnerability in spacetime Ad Inserter – Ad Manager & AdSense Ads, published on 1 Oct 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-2026-19902 in the wild and no public exploit code.

Affected product: spacetime Ad Inserter – Ad Manager & AdSense Ads. 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-2026-19902/ (Markdown: https://insights.sbomify.com/CVE-2026-19902/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-19902
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-19902
- OSV: https://osv.dev/vulnerability/CVE-2026-19902

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-19902/
Summaries are generated and may contain mistakes; the official description above is the record.