Auth bypass in Zalando Skipper
CVE-2026-86043
Skipper is an HTTP router and reverse proxy for service composition. Prior to version 0.27.37, the opaAuthorizeRequestWithBody filter can authorize an oversized request after Skipper truncates the body presented to Open Policy Agent because the input.truncated_body signal is derived from Content-Length rather than the actual read result. In filters/openpolicyagent/openpolicyagent.go, ExtractHttpBodyOptionally truncates bodies at maxBodyBytes, while filters/openpolicyagent/internal/envoy/skipperadapter.go copies the request headers without adding a Content-Length value that reflects the truncation. For an HTTP/1.1 request using Transfer-Encoding: chunked or an HTTP/2 request without Content-Length, a body-inspecting policy that follows the prior mitigation and permits input.truncated_body equal to false can evaluate only the truncated prefix, allow the request, and then forward the full oversized body to the protected upstream. This residual issue is distinct from CVE-2026-50197. This issue is fixed in version 0.27.37.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.005 (39.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 39th percentile — 39.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.005 · change: 0.000
Affected products
- Zalando Skipper — versions < 0.27.37
Weakness classification (CWE)
References
Frequently asked questions
- What is CVE-2026-86043?
- CVE-2026-86043 is a high-severity vulnerability in Zalando Skipper, classified under Incorrect Authorization. CVSS score: 7.5/10. Published 2026-09-16.
- How severe is CVE-2026-86043?
- High severity. CVSS v3 base score is 7.5 out of 10.