Vulnerability-Lookup

GHSA-CHR5-7VJC-3P97

Vulnerability from github – Published: 2026-08-18 12:31 – Updated: 2026-08-18 12:31

Details

The Grav API plugin (getgrav/grav-plugin-api, bundled with Grav 2.0's admin-next/API stack) before version 1.0.14 contains an open redirect weakness in SsoController::sanitizeReturnTo(). The function rejects a literal '//' prefix but does not account for browsers normalizing backslashes to slashes in special (http/https) schemes, so a returnTo value such as '/\evil.com' passes the guard and is later resolved by the browser as the protocol-relative URL '//evil.com'. Following a legitimate OAuth login flow, an attacker-supplied returnTo parameter could redirect an authenticated victim to an attacker-controlled site for post-login phishing. Full browser-side exploitability depends on the admin-next SPA's client-side oauth-callback handler and was not independently verified by the reporter.

Severity

4.2 (Medium)


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

8.6 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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{
  "affected": [],
  "aliases": [
    "CVE-2026-75833"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-601"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-18T12:19:33Z",
    "severity": "HIGH"
  },
  "details": "The Grav API plugin (getgrav/grav-plugin-api, bundled with Grav 2.0\u0027s admin-next/API stack) before version 1.0.14 contains an open redirect weakness in SsoController::sanitizeReturnTo(). The function rejects a literal \u0027//\u0027 prefix but does not account for browsers normalizing backslashes to slashes in special (http/https) schemes, so a returnTo value such as \u0027/\\evil.com\u0027 passes the guard and is later resolved by the browser as the protocol-relative URL \u0027//evil.com\u0027. Following a legitimate OAuth login flow, an attacker-supplied returnTo parameter could redirect an authenticated victim to an attacker-controlled site for post-login phishing. Full browser-side exploitability depends on the admin-next SPA\u0027s client-side oauth-callback handler and was not independently verified by the reporter.",
  "id": "GHSA-chr5-7vjc-3p97",
  "modified": "2026-08-18T12:31:22Z",
  "published": "2026-08-18T12:31:22Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/getgrav/grav/security/advisories/GHSA-x72c-4jc4-8rh6"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-75833"
    },
    {
      "type": "WEB",
      "url": "https://www.vulncheck.com/advisories/grav-api-plugin-open-redirect-via-backslash-bypass"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-75833 (GCVE-0-2026-75833)

Vulnerability from cvelistv5 – Published: 2026-08-18 11:19 – Updated: 2026-08-18 13:42

Title

Grav API Plugin Open Redirect via Backslash Bypass

Summary

Severity

8.6 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

4.2 (Medium)


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

SSVC

Exploitation: poc Automatable: no Technical Impact: total

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-18 13:41 UTC

CWE

CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')

Assigner

VulnCheck mitre root

References

2 references

URL	Tags
https://github.com/getgrav/grav/security/advisori…	vendor-advisory
https://www.vulncheck.com/advisories/grav-api-plu…	third-party-advisory

Impacted products

1 product

Vendor	Product	Version
getgrav	grav	Affected: 0 , < 1.0.14 (semver) Unaffected: 1.0.14 (semver) cpe:2.3:a:getgrav:grav::::::::

Date Public

2026-08-03 00:00

Credits

iaohkut-from-NightWolf-Team

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JSON

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  "containers": {
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        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-75833",
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                  },
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                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-18T13:41:12.267567Z",
                "version": "2.0.3"
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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.

Detection rules are retrieved from Rulezet.

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.

Action not permitted

GHSA-CHR5-7VJC-3P97

CVE-2026-75833 (GCVE-0-2026-75833)

Tags

Sightings

Nomenclature