{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "flask"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.1.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-27205"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-524"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-19T20:45:41Z",
    "nvd_published_at": "2026-02-21T06:17:00Z",
    "severity": "LOW"
  },
  "details": "When the `session` object is accessed, Flask should set the `Vary: Cookie` header. This instructs caches not to cache the response, as it may contain information specific to a logged in user. This is handled in most cases, but some forms of access such as the Python `in` operator were overlooked.\n\nThe severity depends on the application\u0027s use of the session, and the cache\u0027s behavior regarding cookies. The risk depends on all these conditions being met.\n\n1. The application must be hosted behind a caching proxy that does not ignore responses with cookies.\n2. The application does not set a `Cache-Control` header to indicate that a page is private or should not be cached.\n3. The application accesses the session in a way that does not access the values, only the keys, and does not mutate the session.",
  "id": "GHSA-68rp-wp8r-4726",
  "modified": "2026-02-23T22:28:03Z",
  "published": "2026-02-19T20:45:41Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/pallets/flask/security/advisories/GHSA-68rp-wp8r-4726"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-27205"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pallets/flask/commit/089cb86dd22bff589a4eafb7ab8e42dc357623b4"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/pallets/flask"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pallets/flask/releases/tag/3.1.3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Flask session does not add `Vary: Cookie` header when accessed in some ways"
}

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.2.0"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "msgpack"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.2.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-19T21:42:55Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Impact\n\nIf the Unpacker is used repeatedly after an error occurs, the process may crash with a SEGV.\n\nIf the Unpacker is used repeatedly to unpack untrusted input from external sources, it may be vulnerable to a DoS attack.\n\n### Patches\n\nv1.2.1\n\n### Workarounds\n\nUsers should create a new Unpacker instead of reusing the same Unpacker after an error occurs.\n\nApplying the above patch can prevent SEGV, but reusing the Streaming Unpacker after it has encountered an error will not yield correct data. If an error occurs during Streaming Unpacking, the Stream and Streaming Unpacker should be discarded.\n\nTherefore, this is not just a workaround but the correct solution. The above patch only prevents crashes from incorrect usage.",
  "id": "GHSA-6v7p-g79w-8964",
  "modified": "2026-06-19T21:42:55Z",
  "published": "2026-06-19T21:42:55Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/msgpack/msgpack-python/security/advisories/GHSA-6v7p-g79w-8964"
    },
    {
      "type": "WEB",
      "url": "https://github.com/msgpack/msgpack-python/commit/2c56ddb5d0025ed481d962c0f5d62d19dec7476d"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/msgpack/msgpack-python"
    },
    {
      "type": "WEB",
      "url": "https://github.com/msgpack/msgpack-python/releases/tag/v1.2.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "MessagePack for Python: Out-of-bounds read / crash on Unpacker reuse after a caught error"
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "urllib3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2.6.0"
            },
            {
              "fixed": "2.7.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44432"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-409"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-11T14:51:45Z",
    "nvd_published_at": "2026-05-13T16:16:57Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nurllib3\u0027s [streaming API](https://urllib3.readthedocs.io/en/2.7.0/advanced-usage.html#streaming-and-i-o) is designed for the efficient handling of large HTTP responses by reading the content in chunks, rather than loading the entire response body into memory at once.\n\nurllib3 can perform decompression based on the HTTP `Content-Encoding` header (e.g., `gzip`, `deflate`, `br`, or `zstd`). When using the streaming API since version 2.6.0, the library decompresses only the necessary bytes, enabling partial content consumption.\n\nHowever, urllib3 before version 2.7.0 could still decompress the whole response instead of the requested portion in two cases:\n1. During the second `HTTPResponse.read(amt=N)` call when the response was decompressed using the official [Brotli](https://pypi.org/project/brotli/) library.\n2. When `HTTPResponse.drain_conn()` was called after the response had been read and decompressed partially (compression algorithm did not matter here).\n\nThese issues could cause urllib3 to fully decode a small amount of highly compressed data in a single operation. This could result in excessive resource consumption (high CPU usage and massive memory allocation for the decompressed data; CWE-409) on the client side.\n\n\n### Affected usages\n\nApplications and libraries using urllib3 versions earlier than 2.7.0 may be affected when streaming compressed responses from untrusted sources in either of these cases, unless decompression is explicitly disabled:\n\n1. A response encoded with `br` is read incrementally with at least two `HTTPResponse.read(amt=N)` or `HTTPResponse.stream(amt=N)` calls while using the official [Brotli](https://pypi.org/project/brotli/) library.\n2. `HTTPResponse.drain_conn()` is called after response decompression has already started.\n\n\n### Remediation\n\nUpgrade to at least urllib3 version 2.7.0 in which the library:\n1. Is more efficient for reads with Brotli.\n2. Always skips decompression for `HTTPResponse.drain_conn()`.\n\nIf upgrading is not immediately possible, the following workarounds may reduce exposure in specific cases:\n1. For the Brotli-specific issue only, switch from [brotli](https://pypi.org/project/brotli/) to [brotlicffi](https://pypi.org/project/brotlicffi/) until you can upgrade urllib3; the official Brotli package is affected because of https://github.com/google/brotli/issues/1396.\n2. If your code explicitly calls `HTTPResponse.drain_conn()`, call `HTTPResponse.close()` instead when connection reuse is not important.\n\n\n### Credits\n\nThe Brotli-specific issue was reported by @kimkou2024.\n`HTTPResponse.drain_conn()` inefficiency was reported by @Cycloctane.",
  "id": "GHSA-mf9v-mfxr-j63j",
  "modified": "2026-06-08T19:52:23Z",
  "published": "2026-05-11T14:51:45Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-mf9v-mfxr-j63j"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44432"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/urllib3/PYSEC-2026-142.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/urllib3/urllib3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H",
      "type": "CVSS_V4"
    }
  ],
  "summary": "urllib3: Decompression-bomb safeguards bypassed in parts of the streaming API"
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "python-dotenv"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.2.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-28684"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-59",
      "CWE-61"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-21T14:38:57Z",
    "nvd_published_at": "2026-04-20T17:16:33Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\n`set_key()` and `unset_key()` in python-dotenv follow symbolic links when rewriting `.env` files, allowing a local attacker to overwrite arbitrary files via a crafted symlink when a cross-device rename fallback is triggered.\n\n\n### Details\n\nThe `rewrite()` context manager in `dotenv/main.py` is used by both `set_key()` and `unset_key()` to safely modify `.env` files. It works by writing to a temporary file (created in the system\u0027s default temp directory, typically `/tmp`) and then using `shutil.move()` to replace the original file.\n\nWhen the `.env` path is a symbolic link and the temp directory resides on a different filesystem than the target (a common configuration on Linux systems using tmpfs for `/tmp`), the following sequence occurs:\n\n1. `shutil.move()` first attempts `os.rename()`, which fails with an `OSError` because atomic renames cannot cross device boundaries.\n2. On failure, `shutil.move()` falls back to `shutil.copy2()` followed by `os.unlink()`.\n3. `shutil.copy2()` calls `shutil.copyfile()` with `follow_symlinks=True` by default.\n4. This causes the content to be written to the **symlink target** rather than replacing the symlink itself.\n\nAn attacker who has write access to the directory containing a `.env` file can pre-place a symlink pointing to any file that the application process has write access to. When the application (or a privileged process such as a deploy script, Docker entrypoint, or CI pipeline) calls `set_key()` or `unset_key()`, the symlink target is overwritten with the new `.env` content.\n\nThis vulnerability does not require a race condition and is fully deterministic once the preconditions are met.\n\n### Impact\nThe primary impacts are to **integrity** and **availability**:\n\n- **File overwrite / destruction (DoS):** An attacker can cause an application or privileged process to corrupt or destroy configuration files, database configs, or other sensitive files it would not normally have access to modify.\n- **Integrity violation:** The target file\u0027s original content is replaced with `.env`-formatted content controlled by the attacker.\n- **Potential privilege escalation:** In scenarios where a privileged process (running as root or a service account) calls `set_key()`, the attacker can leverage this to write to files beyond their own access level.\n\nThe scope of impact depends on the application using python-dotenv and the privileges under which it runs.\n\n\n### Proof of Concept\n\nThe following script demonstrates the vulnerability. It requires `/tmp` and the user\u0027s home directory to reside on different devices (common on systemd-based Linux systems with tmpfs).\n\n```python\nimport os\nimport sys\nimport tempfile\nfrom dotenv import set_key\n\n# Pre-condition: /tmp must be on a different device than the target directory.\ntmp_dev = os.stat(\"/tmp\").st_dev\nhome_dev = os.stat(os.path.expanduser(\"~\")).st_dev\nassert tmp_dev != home_dev, \"Skipped: /tmp and ~ are on the same device (no cross-device move)\"\n\nwith tempfile.TemporaryDirectory(dir=os.path.expanduser(\"~\")) as workdir:\n    # File an attacker wants to overwrite\n    target = os.path.join(workdir, \"victim_config.txt\")\n    with open(target, \"w\") as f:\n        f.write(\"DB_PASSWORD=supersecret\\n\")\n\n    # Attacker pre-places a symlink at the path the application will use as .env\n    env_symlink = os.path.join(workdir, \".env\")\n    os.symlink(target, env_symlink)\n\n    before = open(target).read()\n\n    # Application writes a new key -- triggers the cross-device fallback\n    set_key(env_symlink, \"INJECTED\", \"attacker_value\")\n\n    after = open(target).read()\n\n    print(\"Before:\", repr(before))\n    print(\"After: \", repr(after))\n    print(\"Symlink target overwritten:\", target)\n```\n\n**Expected output:**\n```\nBefore: \u0027DB_PASSWORD=supersecret\\n\u0027\nAfter:  \"DB_PASSWORD=supersecret\\nINJECTED=\u0027attacker_value\u0027\\n\"\nSymlink target overwritten: /home/user/tmp806nut2g/victim_config.txt\n```\n\n### Remediation\n\nThe fix changes the `rewrite()` context manager in the following ways:\n\n1. **Symlinks are no longer followed by default.** When the `.env` path is a symlink, `rewrite()` now resolves it to the real path before proceeding, or (by default) operates on the symlink entry itself rather than the target.\n2. **A `follow_symlinks: bool = False` parameter** is added to `set_key()` and `unset_key()` for users who explicitly need the old behavior.\n3. **Temp files are written in the same directory** as the target `.env` file (instead of the system temp directory), eliminating the cross-device rename condition entirely.\n4. **`os.replace()` is used instead of `shutil.move()`**, providing atomic replacement without symlink-following fallback behavior.\n\nUsers are advised to upgrade to the patched version as soon as it is available on PyPI.\n\n### Timeline\n\n| Date             | Event                                                                                                                                                                 |\n| ------------ | ---------------------------------------------------------------------------------------------------- |\n| 2026-01-09  | Initial report received from Giorgos Tsigourakos regarding a separate, unrelated issue also located in `rewrite()` |\n| 2026-01-10   | Co-maintainer acknowledged report, requested clarification                                                         |\n| 2026-01-11    | Initial report assessed as not exploitable and closed                                                              |\n| 2026-02-24  | Reporter identified new, distinct cross-device symlink attack vector with deterministic exploitation               |\n| 2026-02-26  | Co-maintainer confirmed vulnerability and shared draft patch                                                       |\n| 2026-02-26  | Reporter validated fix with monkeypatched PoC, proposed CVSS                                                       |\n| 2026-03-01   | Patch merged to main                                                                                               |\n| 2026-03-01   | Patched version released to PyPI                                                                                   |\n| 2026-04-20   | Advisory published                                                                                                 |\n\n### Patches\n\nUpgrade to v.1.2.2 or use the patch from https://github.com/theskumar/python-dotenv/commit/790c5c02991100aa1bf41ee5330aca75edc51311.patch",
  "id": "GHSA-mf9w-mj56-hr94",
  "modified": "2026-04-21T14:38:57Z",
  "published": "2026-04-21T14:38:57Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/theskumar/python-dotenv/security/advisories/GHSA-mf9w-mj56-hr94"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-28684"
    },
    {
      "type": "WEB",
      "url": "https://github.com/theskumar/python-dotenv/commit/790c5c02991100aa1bf41ee5330aca75edc51311"
    },
    {
      "type": "WEB",
      "url": "https://github.com/theskumar/python-dotenv/commit/790c5c02991100aa1bf41ee5330aca75edc51311.patch"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/theskumar/python-dotenv"
    },
    {
      "type": "WEB",
      "url": "https://github.com/theskumar/python-dotenv/releases/tag/v1.2.2"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "python-dotenv: Symlink following in set_key allows arbitrary file overwrite via cross-device rename fallback"
}

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "urllib3"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "1.23"
            },
            {
              "fixed": "2.7.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-44431"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-200"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-05-11T14:51:20Z",
    "nvd_published_at": "2026-05-13T16:16:57Z",
    "severity": "HIGH"
  },
  "details": "### Impact\n\nWhen following cross-origin redirects for requests made using urllib3\u2019s high-level APIs, such as `urllib3.request()`, `PoolManager.request()`, and `ProxyManager.request()`, sensitive headers \u2014 `Authorization`, `Cookie`, and `Proxy-Authorization` (defined in `Retry.DEFAULT_REMOVE_HEADERS_ON_REDIRECT`) \u2014 are stripped by default, as expected.\n\nHowever, cross-origin redirects followed from the low-level API via `ProxyManager.connection_from_url().urlopen(..., assert_same_host=False)` still forward these sensitive headers.\n\n### Affected usage\n\nApplications and libraries using urllib3 versions earlier than 2.7.0 may be affected if they allow cross-origin redirects while making requests through `HTTPConnection.urlopen()` instances created via `ProxyManager.connection_from_url()`.\n\n### Remediation\n\nUpgrade to urllib3 version 2.7.0 or later, in which sensitive headers are stripped from redirects followed by `HTTPConnection`.\n\nIf upgrading is not immediately possible, avoid using this low-level redirect flow for cross-origin redirects. If appropriate for your use case, switch to `ProxyManager.request()`.",
  "id": "GHSA-qccp-gfcp-xxvc",
  "modified": "2026-05-14T20:35:49Z",
  "published": "2026-05-11T14:51:20Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/urllib3/urllib3/security/advisories/GHSA-qccp-gfcp-xxvc"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-44431"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/urllib3/urllib3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "urllib3: Sensitive headers forwarded across origins in proxied low-level redirects"
}

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 1.3.10"
      },
      "package": {
        "ecosystem": "PyPI",
        "name": "Mako"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.3.11"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-41205"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-22"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-16T21:16:40Z",
    "nvd_published_at": "2026-04-23T19:17:29Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\n`TemplateLookup.get_template()` is vulnerable to path traversal when a URI starts with `//` (e.g., `//../../../secret.txt`). The root cause is an inconsistency between two slash-stripping implementations:\n\n- `Template.__init__` strips **one** leading `/` using `if`/slice\n- `TemplateLookup.get_template()` strips **all** leading `/` using `re.sub(r\"^\\/+\", \"\")`\n\nWhen a URI like `//../../../../etc/passwd` is passed:\n1. `get_template()` strips all `/` \u2192 `../../../../etc/passwd` \u2192 file found via `posixpath.join(dir_, u)`\n2. `Template.__init__` strips one `/` \u2192 `/../../../../etc/passwd` \u2192 `normpath` \u2192 `/etc/passwd`\n3. `/etc/passwd`.startswith(`..`) \u2192 `False` \u2192 **check bypassed**\n\n### Impact\n\nArbitrary file read: any file readable by the process can be returned as rendered template content when an application passes untrusted input directly to `TemplateLookup.get_template()`.\n\nNote: this is exploitable at the library API level. HTTP-based exploitation is mitigated by Python\u0027s `BaseHTTPRequestHandler` which normalizes double-slash prefixes since CPython gh-87389. Applications using other HTTP servers that do not normalize paths may be affected.\n\n### Fix\n\nChanged `Template.__init__` to use `lstrip(\"/\")` instead of stripping only a single leading slash, so both code paths handle leading slashes consistently.",
  "id": "GHSA-v92g-xgxw-vvmm",
  "modified": "2026-06-05T14:13:04Z",
  "published": "2026-04-16T21:16:40Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sqlalchemy/mako/security/advisories/GHSA-v92g-xgxw-vvmm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-41205"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sqlalchemy/mako/commit/e05ac61989a7fb9dd7dcde6cfd72dc48328719a3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/pypa/advisory-database/tree/main/vulns/mako/PYSEC-2026-88.yaml"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sqlalchemy/mako"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sqlalchemy/mako/releases/tag/rel_1_3_11"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:P",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Mako: Path traversal via double-slash URI prefix in TemplateLookup"
}