Auth bypass in Alluxio
CVE-2026-79787
Alluxio's S3 REST proxy fails to verify AWS Signature Version 4 signatures in its default configuration, allowing unauthenticated attackers to spoof user identity. Attackers can extract usernames from unsigned Authorization headers and impersonate any user, including service accounts, to read, write, and delete arbitrary data.
Vulnerability class: Broken Authentication
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.005 (37.5th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 38th percentile — 37.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.001
Affected products
Weakness classification (CWE)
References
- github.com/Alluxio/alluxio (product)
- github.com/Alluxio/alluxio/issues/18755 (issue-tracking)
- github.com/Alluxio/alluxio/blob/v2.9.5/core/server/proxy/src/main/java/alluxio/… (technical-description)
- www.vulncheck.com/advisories/alluxio-through-2.9.5-s3-rest-proxy-authentication… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-79787?
- CVE-2026-79787 is a critical-severity vulnerability in Alluxio, classified under Improper Authentication. CVSS score: 9.8/10. Published 2026-08-25.
- How severe is CVE-2026-79787?
- Critical severity. CVSS v3 base score is 9.8 out of 10.