How severe is CVE-2026-54735?

CVE-2026-54735 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-54735 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-54735?

CVE-2026-54735 affects Prebid Prebid Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-54735?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-54735 published?

CVE-2026-54735 was published on 2026-07-29 and last updated on 2026-08-18.

CVE-2026-54735

CVE-2026-54735 is a critical-severity vulnerability in Prebid Prebid Server with a CVSS 3.x base score of 10.0. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-918.

Key facts

Severity: Critical (CVSS 3.x base score 10.0)
EPSS exploit prediction: 0% (28th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-918
Affected product: Prebid Prebid Server
Published: 2026-07-29
Last modified: 2026-08-18

Description

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.

Frequently asked questions

What is CVE-2026-54735?: 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.
How severe is CVE-2026-54735?: CVE-2026-54735 has a CVSS 3.x base score of 10.0, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-54735 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-54735?: CVE-2026-54735 affects Prebid Prebid Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-54735?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-54735 published?: CVE-2026-54735 was published on 2026-07-29 and last updated on 2026-08-18.

References

Affected products (1)

cpe:2.3:a:prebid:prebid_server:*:*:*:*:*:go:*:*

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