Security readout for executives and security teams
Plain-English summary
Alluxio’s S3 REST proxy can trust a claimed identity without verifying the request’s AWS Signature Version 4 signature. On affected systems, an unauthenticated network attacker could impersonate users or service accounts and read, alter, or delete data. The supplied sources describe versions through 2.9.5 and default configuration as vulnerable.
Executive priority
Treat exposed affected proxies as an immediate containment and remediation priority because compromise could permit wholesale data theft, manipulation, or deletion. Prioritize internet-facing and sensitive-data environments first. Do not claim compromise solely from version detection; review access and data-operation logs for supporting evidence.
Technical view
The proxy extracts usernames from attacker-controlled Authorization headers but does not validate the associated AWS Signature Version 4 signature. This creates a network-accessible authentication bypass with no privileges or user interaction required. The supplied CVSS 3.1 score is 9.8, reflecting potential complete confidentiality, integrity, and availability impact.
Likely exposure
Highest risk applies where an Alluxio S3 REST proxy through version 2.9.5 uses the affected default behavior and is reachable by untrusted networks. Internal-only proxies remain exposed to malicious or compromised internal clients. The bundle does not establish exposure for deployments without the S3 proxy or with independent authentication controls.
Exploitation context
The technique requires network access and a crafted identity claim, without prior credentials or user interaction. However, the supplied bundle marks this CVE as absent from KEV and provides no evidence of active exploitation. Public proof-of-concept availability is not established by the supplied evidence.
Researcher notes
CWE-287 applies because identity is accepted without authenticating the request. The key review point is whether every S3 request receives cryptographic signature verification before user context is established. The bundle does not identify a fixed release, vendor patch, exploitation telemetry, or confirmed proof of concept; validate remediation against current Alluxio guidance.
Mitigation direction
- Inventory Alluxio S3 REST proxy deployments and identify versions through 2.9.5.
- Restrict proxy access to trusted networks while remediation is evaluated.
- Apply vendor-recommended fixes or configuration changes when Alluxio publishes confirmed guidance.
- Use an independently authenticated gateway if continued proxy operation is unavoidable.
- Protect critical data with backups and least-privilege service-account permissions.
Validation and detection
- Confirm whether the S3 REST proxy is enabled and network reachable.
- Record deployed Alluxio versions and flag 2.9.5 or earlier for review.
- Review configuration for signature verification or independent upstream authentication.
- Inspect logs for unexpected identities, service-account use, and abnormal data operations.
- Verify compensating access controls reject unauthenticated requests without testing destructive actions.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-287: Credential and account abuse lookup
Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-79787 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
2 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N——VulnCheckVulnerability scoring details
Base CVSS 4.0 score
9.3CriticalVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/Alluxio/alluxioCVE reference, VulnCheck · product
- https://github.com/Alluxio/alluxio/issues/18755CVE reference, VulnCheck · issue-tracking
- https://github.com/Alluxio/alluxio/blob/v2.9.5/core/server/proxy/src/main/java/alluxio/proxy/s3/S3RestUtils.javaCVE reference, VulnCheck · technical-description
- VulnCheck Advisory: Alluxio through 2.9.5 S3 REST Proxy Authentication Bypass via Unverified Request SignatureCVE reference, VulnCheck · third-party-advisory
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Authentication
Improper Authentication represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.