CVE-2026-54735: Prebid Server is an open-source solution for running real-time advertising auctions in the cloud

Q: How do I fix CVE-2026-54735?

prebid server: upgrade to 4.4.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-54735 being exploited?

CVE-2026-54735 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-54735 affect?

CVE-2026-54735 affects prebid server. Severity is critical (CVSS 10.0). 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 prope

Q: How urgent is CVE-2026-54735?

Priority 55/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

This month

CRITICAL 10.0REMOTEUPGRADE

CVE-2026-54735 is a critical-severity flaw (CVSS 10.0) affecting prebid server. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 en

Why this priority

Critical severity
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	10.0 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-918
Published	2026-07-29
Last modified	2026-10-23

Publisher (CNA): GitHub, Inc. · Vendor: prebid

Last updated 2026-10-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-07-29 16:17 UTCPublished CVE record published
2026-10-23 23:10 UTCUpdated Record last modified

prebid prebid server UPGRADE

Affected: < 4.4.0

Fixed in: 4.4.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy prebid-server || rpm -q prebid-server || prebid-server --version

2. UPGRADE to 4.4.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade prebid-server

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade prebid-server

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Exact fixes by distribution

Go · github.com/prebid/prebid-server/v4 · FIXED · 4.4.0 · vulnerable: < 4.4.0 · source

go get github.com/prebid/prebid-server/v4@v4.4.0 go list -m github.com/prebid/prebid-server/v4

Go · github.com/prebid/prebid-server/v3 · NO FIX YET · vulnerable: <= 3.30.0 · source

Go · github.com/prebid/prebid-server/v2 · NO FIX YET · vulnerable: <= 2.32.0 · source

Go · github.com/prebid/prebid-server · NO FIX YET · vulnerable: <= 0.275.0 · source

Fedora 46 · python-openslide · FIXED · 1.4.7-1.fc46 · FEDORA-2026-336bea884e · source

sudo dnf upgrade --advisory=FEDORA-2026-336bea884e

Fedora ELN · valgrind · FIXED · 3.28.0-1.eln159 · FEDORA-2026-c593ef1d15 · source

sudo dnf upgrade --advisory=FEDORA-2026-c593ef1d15

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-54735?

prebid server: upgrade to 4.4.0. Exact commands for each OS are on this page.

Is CVE-2026-54735 being exploited?

CVE-2026-54735 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-54735 affect?

CVE-2026-54735 affects prebid server. Severity is critical (CVSS 10.0). 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 prope

How urgent is CVE-2026-54735?

Priority 55/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

References

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