CVE-2026-54735Network attack vector

Unauthenticated internal service access via bidder URL injection

Published Jul 29, 2026 · Updated Jul 29, 2026

SSRF in Prebid Server before 4.4.0 allows remote attackers to send HTTP requests to unintended endpoints through crafted bid parameters. Affected bidder adapters interpolate attacker-controlled host or subdomain values into outbound URL templates without rejecting path, query, fragment, user-info, or scheme syntax. No authentication or user interaction is required; reachability depends on an affected adapter being enabled, and requests can reach internal services or sensitive server endpoints.

CVSS severity10.0
Critical
EPSS probability0.34%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

SSRF in Prebid Server before 4.4.0 allows remote attackers to send HTTP requests to unintended endpoints through crafted bid parameters. Affected bidder adapters interpolate attacker-controlled host or subdomain values into outbound URL templates without rejecting path, query, fragment, user-info, or scheme syntax. No authentication or user interaction is required; reachability depends on an affected adapter being enabled, and requests can reach internal services or sensitive server endpoints.

The record

CVE
CVE-2026-54735
Published
Jul 29, 2026
Updated
Jul 29, 2026
Vendor
Prebid.org
Product
Prebid Server
Classifications
CWE-918, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 4.4.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Prebid.org · Prebid Serverversion=< 4.4.0

Published CVSS scores

10.0GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo