Vulnerability-Lookup

CVE-2026-102894 (GCVE-0-2026-102894)

Vulnerability from cvelistv5 – Published: 2026-11-04 21:18 – Updated: 2026-11-06 11:34

Title

GPUStack: SAML callback trusts an unverified SAMLResponse, allowing authentication bypass and account takeover

Summary

GPUStack is an open-source GPU cluster manager for AI model serving and GPU instance provisioning. From 0.7.1 until 2.2.2, the /auth/saml/callback endpoint decoded SAML XML, used its NameID and attributes to resolve or provision a user, and minted a gpustack_session JWT without calling OneLogin_Saml2_Auth.process_response to verify the signature, issuer, audience, destination, or time conditions. Any network client could submit an identity for an existing user, including an administrator, or provision a new non-administrator account, even when SAML was not configured. Response and Assertion identifiers were not consumed, so captured signed responses could also be replayed. This issue is fixed in version 2.2.2.

Severity

9.1 (Critical)


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

SSVC

Exploitation: none Automatable: yes Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-11-06 04:56 UTC

CWE

CWE-294 - Authentication Bypass by Capture-replay
CWE-347 - Improper Verification of Cryptographic Signature

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7789 records in the last 180 days details

References

6 references

URL	Tags
https://github.com/gpustack/gpustack/security/adv…	x_refsource_CONFIRM
https://github.com/gpustack/gpustack/pull/5753	x_refsource_MISC
https://github.com/gpustack/gpustack/pull/5923	x_refsource_MISC
https://github.com/gpustack/gpustack/commit/705ed…	x_refsource_MISC
https://github.com/gpustack/gpustack/commit/adc6d…	x_refsource_MISC
https://github.com/gpustack/gpustack/releases/tag…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
gpustack	gpustack	Affected: >= 0.7.1, < 2.2.2	guessed

Show details on NVD website

JSON

To clipboard

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}

FKIE_CVE-2026-102894

Vulnerability from fkie_nvd - Published: 2026-11-04 22:17 - Updated: 2026-11-06 12:17

Severity

9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/gpustack/gpustack/commit/705edbe1b5feec63959306daecd640e1c70eced2
	security-advisories@github.com	https://github.com/gpustack/gpustack/commit/adc6d82be34e48390720a1361df616e2ea9d6d45
	security-advisories@github.com	https://github.com/gpustack/gpustack/pull/5753
	security-advisories@github.com	https://github.com/gpustack/gpustack/pull/5923
	security-advisories@github.com	https://github.com/gpustack/gpustack/releases/tag/v2.2.2
	security-advisories@github.com	https://github.com/gpustack/gpustack/security/advisories/GHSA-62m9-f875-rqw6

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "gpustack",
          "vendor": "gpustack",
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    }
  ],
  "id": "CVE-2026-102894",
  "lastModified": "2026-11-06T12:17:15.083",
  "metrics": {
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    {
      "source": "security-advisories@github.com",
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      "url": "https://github.com/gpustack/gpustack/releases/tag/v2.2.2"
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      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-62M9-F875-RQW6

Vulnerability from github – Published: 2026-11-10 15:57 – Updated: 2026-11-10 15:57

Summary

GPUStack: SAML callback trusts an unverified SAMLResponse, allowing authentication bypass and account takeover

Details

Impact

The callback Base64-decodes the posted XML, reads NameID and attributes, resolves or provisions the user, and mints a gpustack_session JWT — but never calls OneLogin_Saml2_Auth.process_response(), the step that verifies the signature, issuer, audience, destination, and time conditions.

No credentials are required, and SAML SSO does not even need to be configured. The callback processes the payload and issues a session regardless of whether SAML is set up, so every deployment is affected, not only SAML-enabled ones. Anyone who can reach the endpoint over the network can authenticate as an arbitrary identity by posting a response that names it:

If the name matches an existing user (e.g. an administrator), the attacker receives that user's session — full account takeover, including administrator access.
Otherwise, a new non-admin user is provisioned.

Administrator access grants full control over the deployment and the infrastructure it manages. Because Response/Assertion IDs are never consumed, a captured signed response also replays indefinitely.

Precondition: network reachability to /auth/saml/callback. SAML SSO configuration is not required. A full proof-of-concept is available privately to maintainers.

Patches

Fixed in gpustack 2.2.2: - The SAML callback now validates the response via OneLogin_Saml2_Auth.process_response() — signature, issuer, audience, destination, and time conditions — and rejects responses that fail, so forged or replayed assertions are no longer accepted. - The SAML and OIDC login/callback routes are now gated to run only when that provider is the configured active provider, so a deployment that has not enabled the provider no longer parses attacker-supplied IdP payloads.

Workarounds

There is no effective configuration-level workaround — disabling or not configuring SAML does not mitigate this on affected versions, since the callback runs regardless. Until upgraded, block network access to /auth/saml/callback (e.g. at a reverse proxy / ingress).

Credit

Reported privately by Austin Chu, Sohee Kim, and Corban Villa (UC Berkeley security research project), and independently, earlier, by a researcher who wishes to remain anonymous.

Severity

9.1 (Critical)


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

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{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "gpustack"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.7.1"
            },
            {
              "fixed": "2.2.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-102894"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-294",
      "CWE-347"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-11-10T15:57:15Z",
    "nvd_published_at": "2026-11-04T22:17:44Z",
    "severity": "CRITICAL"
  },
  "details": "### Impact\n\nThe callback Base64-decodes the posted XML, reads NameID and attributes, resolves or provisions the user, and mints a gpustack_session JWT \u2014 but never calls OneLogin_Saml2_Auth.process_response(), the step that verifies the signature, issuer, audience, destination, and time conditions.\n\nNo credentials are required, and SAML SSO does not even need to be configured. The callback processes the payload and issues a session regardless of whether SAML is set up, so every deployment is affected, not only SAML-enabled ones. Anyone who can reach the endpoint over the network can authenticate as an arbitrary identity by posting a response that names it:\n\n- If the name matches an existing user (e.g. an administrator), the attacker receives that user\u0027s session \u2014 full account takeover, including administrator access.\n- Otherwise, a new non-admin user is provisioned.\n\nAdministrator access grants full control over the deployment and the infrastructure it manages. Because Response/Assertion IDs are never consumed, a captured signed response also replays indefinitely.\n\nPrecondition: network reachability to /auth/saml/callback. SAML SSO configuration is not required. A full proof-of-concept is available privately to maintainers.\n\n\n### Patches\n\nFixed in gpustack 2.2.2:\n- The SAML callback now validates the response via OneLogin_Saml2_Auth.process_response() \u2014 signature, issuer, audience, destination, and time conditions \u2014 and rejects responses that fail, so forged or replayed assertions are no longer accepted.\n- The SAML and OIDC login/callback routes are now gated to run only when that provider is the configured active provider, so a deployment that has not enabled the provider no longer parses attacker-supplied IdP payloads.\n\n### Workarounds\n\nThere is no effective configuration-level workaround \u2014 disabling or not configuring SAML does not mitigate this on affected versions, since the callback runs regardless. Until upgraded, block network access to /auth/saml/callback (e.g. at a reverse proxy / ingress).\n\n### Credit\n\nReported privately by Austin Chu, Sohee Kim, and Corban Villa (UC Berkeley\nsecurity research project), and independently, earlier, by a researcher who wishes to remain anonymous.",
  "id": "GHSA-62m9-f875-rqw6",
  "modified": "2026-11-10T15:57:15Z",
  "published": "2026-11-10T15:57:15Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/gpustack/gpustack/security/advisories/GHSA-62m9-f875-rqw6"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-102894"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gpustack/gpustack/pull/5753"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gpustack/gpustack/pull/5923"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gpustack/gpustack/commit/705edbe1b5feec63959306daecd640e1c70eced2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gpustack/gpustack/commit/adc6d82be34e48390720a1361df616e2ea9d6d45"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/gpustack/gpustack"
    },
    {
      "type": "WEB",
      "url": "https://github.com/gpustack/gpustack/releases/tag/v2.2.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "GPUStack: SAML callback trusts an unverified SAMLResponse, allowing authentication bypass and account takeover"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

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Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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Action not permitted

CVE-2026-102894 (GCVE-0-2026-102894)

FKIE_CVE-2026-102894

GHSA-62M9-F875-RQW6

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