{"id":"CVE-2026-79787","title":"Alluxio's S3 REST proxy fails to verify AWS Signature Version 4 signatures in its default configuration, allowing unauthenticated attackers to spoof user identity","summary":"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 i…","severity":"critical","cvss":9.8,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","cwe":["CWE-287"],"published":"2026-08-25","updated":"2026-09-24","sourceUpdated":"2026-09-24T20:43:32.537","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-79787","references":[{"url":"https://github.com/Alluxio/alluxio","label":"disclosure@vulncheck.com"},{"url":"https://github.com/Alluxio/alluxio/blob/v2.9.5/core/server/proxy/src/main/java/alluxio/proxy/s3/S3RestUtils.java","label":"disclosure@vulncheck.com"},{"url":"https://github.com/Alluxio/alluxio/issues/18755","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/alluxio-through-2.9.5-s3-rest-proxy-authentication-bypass-via-unverified-request-signature","label":"disclosure@vulncheck.com"},{"url":"https://github.com/Alluxio/alluxio/issues/18755","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd"],"epss":0.00641,"epssPercentile":0.48445,"ingestedAt":"2026-09-24T20:51:40.227Z","slug":"CVE-2026-79787","body":"## Overview\n\nAlluxio'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.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"midnight","depthScore":54,"depthScoreParts":{"impact":53.9,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}