CVE-2026-65604: Input Validation Flaw (CVSS 8.2)

Description

Skipper contains an incomplete fix for CVE-2026-50197 in which oversized request bodies bypass Open Policy Agent (OPA) deny-on-presence Rego policies. When a request body exceeds the configured maxBodyBytes limit, Skipper forwards the full payload to the upstream service while OPA evaluates against an empty parsed_body, so policies that deny requests based on body content are not enforced and forbidden actions proceed. No fixed version is available; v0.27.26 adds documentation guidance only.

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CVSS v3.1 Score

8.2

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

EPSS — Exploit Prediction

0.0029

Probability of exploitation

0.21%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-20 Improper Input Validation

References

Other References

https://github.com/zalando/skipper/security/advisories/GHSA-8qqm-fp2q-v734 https://www.vulncheck.com/advisories/skipper-incomplete-fix-for-cve-2026-50197-policy-bypass https://github.com/zalando/skipper/security/advisories/GHSA-8qqm-fp2q-v734

Frequently Asked Questions

What is CVE-2026-65604? +

Skipper contains an incomplete fix for CVE-2026-50197 in which oversized request bodies bypass Open Policy Agent (OPA) deny-on-presence Rego policies. When a request body exceeds the configured maxBodyBytes limit, Skipper forwards the full payload to the upstream service while OPA evaluates against an empty parsed_body, so policies that deny requests based on body content are not enforced and forbidden actions proceed. No fixed version is available; v0.27.26 adds documentation guidance only. It has a CVSS v3.1 base score of 8.2 (HIGH).

How severe is CVE-2026-65604? +

CVE-2026-65604 has a CVSS v3.1 score of 8.2 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0029, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-65604? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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