---
title: "CVE-2026-54735: prebid-server's request forgery vulnerability allows for possible host environment data extraction"
url: https://erroneo.us/security/cve/CVE-2026-54735/
description: "CVE-2026-54735 (github.com/prebid/prebid-server/v4 (Go)): Prebid Server is an open-source solution for running real-time advertising auctions in the cloud.…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-07-29
date_modified: 2026-07-29
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-54735"
kev: false
cvss: 10
epss: 0.00611
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2026-54735: prebid-server's request forgery vulnerability allows for possible host environment data extraction

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
- EPSS 0.6% , percentile 49: FIRST’s model estimates a 0.6% chance of exploitation activity in the next 30 days, higher than 49% of all scored CVEs (low). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes github.com/prebid/prebid-server/v4 (Go) < 4.4.0, fixed in 4.4.0 ; github.com/prebid/prebid-server/v3 (Go) <= 3.30.0, no fixed version listed ; github.com/prebid/prebid-server/v2 (Go) <= 2.32.0, no fixed version listed ; github.com/prebid/prebid-server (Go) <= 0.275.0, no fixed version listed . Check your lockfile, including transitive dependencies.

## What it is

Prebid Server is an open-source solution for running real-time advertising auctions in the cloud. Prior to version 4.4.0, certain bidder adapters in Prebid Server interpolate user-supplied parameters into outbound request URLs without properly validating host and subdomain values, allowing crafted bid request parameters to cause server-side requests to unintended destinations and potentially expose internal network services or sensitive server endpoints. This issue is fixed in version 4.4.0.

## Affected packages

- Go `github.com/prebid/prebid-server/v4` < 4.4.0 → fixed: 4.4.0
- Go `github.com/prebid/prebid-server/v3` <= 3.30.0 → fixed: none listed
- Go `github.com/prebid/prebid-server/v2` <= 2.32.0 → fixed: none listed
- Go `github.com/prebid/prebid-server` <= 0.275.0 → fixed: none listed

## Affected products (CVE record)

- prebid prebid-server: < 4.4.0

## Severity

- GitHub_M CVSS 3.1: 10 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`
- GitHub CVSS 3.1: 10.0 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation none , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 0.61% probability of exploitation activity in the next 30 days; percentile 49.

## Sources

- [GitHub Advisory GHSA-4p3g-4hcj-wpvx](https://github.com/advisories/GHSA-4p3g-4hcj-wpvx)
- [CVE.org record CVE-2026-54735](https://www.cve.org/CVERecord?id=CVE-2026-54735)
- [NVD entry CVE-2026-54735](https://nvd.nist.gov/vuln/detail/CVE-2026-54735)
- [github.com](https://github.com/prebid/prebid-server/security/advisories/GHSA-4p3g-4hcj-wpvx)
- [github.com](https://github.com/prebid/prebid-server/pull/4802)
- [github.com](https://github.com/prebid/prebid-server/commit/494ac271cd4b5024df9123ef25ca3cff96390be3)
- [github.com](https://github.com/prebid/prebid-server/releases/tag/v4.4.0)

---
Source page: https://erroneo.us/security/cve/CVE-2026-54735/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt