CVE-2026-66883

The full cvelistV5 record. Download as CVE-2026-66883.json.

{
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              "content": {
                "id": "CVE-2026-66883",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-08-04T12:27:16.535019Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
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        "providerMetadata": {
          "dateUpdated": "2026-08-04T12:27:58.024Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
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            "tags": [
              "exploit"
            ],
            "url": "https://github.com/erlef/oidcc_plug/security/advisories/GHSA-w5r8-m75h-98fc"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:erlef:oidcc_plug:*:*:*:*:*:erlang:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "Elixir.Oidcc.Plug.Authorize",
            "Elixir.Oidcc.Plug.AuthorizationCallback"
          ],
          "packageName": "oidcc_plug",
          "packageURL": "pkg:hex/oidcc_plug",
          "product": "oidcc_plug",
          "programFiles": [
            "lib/oidcc/plug/authorize.ex",
            "lib/oidcc/plug/authorization_callback.ex"
          ],
          "programRoutines": [
            {
              "name": "'Elixir.Oidcc.Plug.Authorize':call/2"
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            {
              "name": "'Elixir.Oidcc.Plug.AuthorizationCallback':call/2"
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          "repo": "https://github.com/erlef/oidcc_plug",
          "vendor": "Erlang Ecosystem Foundation",
          "versions": [
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              "lessThan": "0.5.0",
              "status": "affected",
              "version": "0.1.0-alpha.3",
              "versionType": "semver"
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          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:erlef:oidcc_plug:*:*:*:*:*:erlang:*:*"
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          "defaultStatus": "unaffected",
          "modules": [
            "Elixir.Oidcc.Plug.Authorize",
            "Elixir.Oidcc.Plug.AuthorizationCallback"
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          "packageName": "erlef/oidcc_plug",
          "packageURL": "pkg:github/erlef/oidcc_plug",
          "product": "oidcc_plug",
          "programFiles": [
            "lib/oidcc/plug/authorize.ex",
            "lib/oidcc/plug/authorization_callback.ex"
          ],
          "programRoutines": [
            {
              "name": "'Elixir.Oidcc.Plug.Authorize':call/2"
            },
            {
              "name": "'Elixir.Oidcc.Plug.AuthorizationCallback':call/2"
            }
          ],
          "repo": "https://github.com/erlef/oidcc_plug",
          "vendor": "Erlang Ecosystem Foundation",
          "versions": [
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              "lessThan": "f15e52c5750aaba701104b10ed96cfac063bd557",
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      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Mathias Polligkeit"
        },
        {
          "lang": "en",
          "type": "remediation developer",
          "value": "Jonatan M\u00e4nnchen / EEF"
        },
        {
          "lang": "en",
          "type": "remediation reviewer",
          "value": "Mathias Polligkeit"
        },
        {
          "lang": "en",
          "type": "coordinator",
          "value": "Jonatan M\u00e4nnchen / EEF"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
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              "value": "<p>Improper Handling of Case Sensitivity vulnerability in Erlang Ecosystem Foundation oidcc_plug (<code>Oidcc.Plug.Authorize</code> module) renders the user agent session binding inert, removing a defense in depth control against replay of a stolen session.</p>\n<p>This vulnerability is associated with program files <code>lib/oidcc/plug/authorize.ex</code> and <code>lib/oidcc/plug/authorization_callback.ex</code>, and program routines <code>Oidcc.Plug.Authorize.call/2</code> and <code>Oidcc.Plug.AuthorizationCallback.call/2</code>.</p>\n<p><code>Oidcc.Plug.Authorize.call/2</code> reads the initiating client's user agent with <code>get_req_header(conn, \"User-Agent\")</code>. Plug lowercases incoming header names, but <code>get_req_header/2</code> matches the supplied key exactly and performs no normalization of its own, so the mixed-case lookup always returns an empty list and <code>nil</code> is written into the session. On the callback side, <code>Oidcc.Plug.AuthorizationCallback</code> treats a stored <code>nil</code> user agent as nothing to compare and returns <code>:ok</code> without inspecting the request. The two behaviours combine so that the check passes unconditionally on every request, including for deployments that explicitly opted in with <code>check_useragent: true</code>, and an authorization callback can be completed from a different user agent than the one that initiated the flow without detection. The check fails open silently, with no error and no log entry, so a deployment cannot tell the binding is absent.</p>\n<p>The impact is limited to defense in depth. The inert check does not by itself allow an attacker to complete an authorization flow; it removes one layer that would otherwise hinder use of a stolen or leaked session, such as an exfiltrated session cookie replayed from a different client. The CSRF/state, nonce, and PKCE checks are unaffected and continue to function. Deployments that never enabled <code>check_useragent</code> are not affected in practice, since they never expected the binding. The corresponding lookup in <code>Oidcc.Plug.AuthorizationCallback</code> correctly uses the lowercase key and is not affected.</p>\n<p>This issue affects oidcc_plug: from 0.1.0-alpha.3 before 0.5.0.</p>"
            },
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              "value": "Improper Handling of Case Sensitivity vulnerability in Erlang Ecosystem Foundation oidcc_plug (`Oidcc.Plug.Authorize` module) renders the user agent session binding inert, removing a defense in depth control against replay of a stolen session.\n\nThis vulnerability is associated with program files `lib/oidcc/plug/authorize.ex` and `lib/oidcc/plug/authorization_callback.ex`, and program routines `Oidcc.Plug.Authorize.call/2` and `Oidcc.Plug.AuthorizationCallback.call/2`.\n\n`Oidcc.Plug.Authorize.call/2` reads the initiating client's user agent with `get_req_header(conn, \"User-Agent\")`. Plug lowercases incoming header names, but `get_req_header/2` matches the supplied key exactly and performs no normalization of its own, so the mixed-case lookup always returns an empty list and `nil` is written into the session. On the callback side, `Oidcc.Plug.AuthorizationCallback` treats a stored `nil` user agent as nothing to compare and returns `:ok` without inspecting the request. The two behaviours combine so that the check passes unconditionally on every request, including for deployments that explicitly opted in with `check_useragent: true`, and an authorization callback can be completed from a different user agent than the one that initiated the flow without detection. The check fails open silently, with no error and no log entry, so a deployment cannot tell the binding is absent.\n\nThe impact is limited to defense in depth. The inert check does not by itself allow an attacker to complete an authorization flow; it removes one layer that would otherwise hinder use of a stolen or leaked session, such as an exfiltrated session cookie replayed from a different client. The CSRF/state, nonce, and PKCE checks are unaffected and continue to function. Deployments that never enabled `check_useragent` are not affected in practice, since they never expected the binding. The corresponding lookup in `Oidcc.Plug.AuthorizationCallback` correctly uses the lowercase key and is not affected.\n\nThis issue affects oidcc_plug: from 0.1.0-alpha.3 before 0.5.0."
            }
          ],
          "value": "Improper Handling of Case Sensitivity vulnerability in Erlang Ecosystem Foundation oidcc_plug (Oidcc.Plug.Authorize module) renders the user agent session binding inert, removing a defense in depth control against replay of a stolen session.\n\nThis vulnerability is associated with program files lib/oidcc/plug/authorize.ex and lib/oidcc/plug/authorization_callback.ex, and program routines Oidcc.Plug.Authorize.call/2 and Oidcc.Plug.AuthorizationCallback.call/2.\n\nOidcc.Plug.Authorize.call/2 reads the initiating client's user agent with get_req_header(conn, \"User-Agent\"). Plug lowercases incoming header names, but get_req_header/2 matches the supplied key exactly and performs no normalization of its own, so the mixed-case lookup always returns an empty list and nil is written into the session. On the callback side, Oidcc.Plug.AuthorizationCallback treats a stored nil user agent as nothing to compare and returns :ok without inspecting the request. The two behaviours combine so that the check passes unconditionally on every request, including for deployments that explicitly opted in with check_useragent: true, and an authorization callback can be completed from a different user agent than the one that initiated the flow without detection. The check fails open silently, with no error and no log entry, so a deployment cannot tell the binding is absent.\n\nThe impact is limited to defense in depth. The inert check does not by itself allow an attacker to complete an authorization flow; it removes one layer that would otherwise hinder use of a stolen or leaked session, such as an exfiltrated session cookie replayed from a different client. The CSRF/state, nonce, and PKCE checks are unaffected and continue to function. Deployments that never enabled check_useragent are not affected in practice, since they never expected the binding. The corresponding lookup in Oidcc.Plug.AuthorizationCallback correctly uses the lowercase key and is not affected.\n\nThis issue affects oidcc_plug: from 0.1.0-alpha.3 before 0.5.0."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-60",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-60 Reusing Session IDs (aka Session Replay)"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "attackVector": "NETWORK",
            "baseScore": 6.3,
            "baseSeverity": "MEDIUM",
            "privilegesRequired": "NONE",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "NONE",
            "subConfidentialityImpact": "NONE",
            "subIntegrityImpact": "NONE",
            "userInteraction": "NONE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N",
            "version": "4.0",
            "vulnAvailabilityImpact": "NONE",
            "vulnConfidentialityImpact": "NONE",
            "vulnIntegrityImpact": "LOW",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
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              "value": "GENERAL"
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      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-178",
              "description": "CWE-178 Improper Handling of Case Sensitivity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-04T11:46:05.191Z",
        "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "shortName": "EEF"
      },
      "references": [
        {
          "tags": [
            "vendor-advisory",
            "related"
          ],
          "url": "https://github.com/erlef/oidcc_plug/security/advisories/GHSA-w5r8-m75h-98fc"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://cna.erlef.org/cves/CVE-2026-66883.html"
        },
        {
          "tags": [
            "related"
          ],
          "url": "https://osv.dev/vulnerability/EEF-CVE-2026-66883"
        },
        {
          "tags": [
            "patch"
          ],
          "url": "https://github.com/erlef/oidcc_plug/commit/f15e52c5750aaba701104b10ed96cfac063bd557"
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "title": "Oidcc.Plug.Authorize user agent session binding inert due to case-sensitive header lookup"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
    "assignerShortName": "EEF",
    "cveId": "CVE-2026-66883",
    "datePublished": "2026-08-04T11:46:05.191Z",
    "dateReserved": "2026-07-28T04:15:10.240Z",
    "dateUpdated": "2026-08-04T12:27:58.024Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2"
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