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Sicherheitslücken in python-urllib3

In den letzten 30 Tagen veröffentlichte Sicherheitslücken für python-urllib3: 3. Davon im KEV-Katalog: 0.

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Sicherheitslücken: 22

  1. CVE-2026-97689

    Hoch · CVSS 8.9EPSS 0,34%Korrektur verfügbar

    urllib3: HTTPResponse.stream()/read_chunked() buffers an unbounded chunk-size line into memory

    urllib3 is an HTTP client library for Python. From 1.10.3 until 2.8.0, the HTTPResponse.read_chunked and HTTPResponse.stream methods can allocate unbounded memory because the streaming chunk parser buffers the chunk-size field until newline or EOF without a length bound. The trigger is that a malicious server returns Transfer-Encoding: chunked followed by a very long run of bytes without a newline. The attack mechanism is that a malicious HTTP server sends a very long unterminated chunk-size line. The impact is that unbounded memory allocation can exhaust the client process. This issue is fixed in version 2.8.0.

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  2. CVE-2026-97688

    Mittel · CVSS 6.9EPSS 0,29%Korrektur verfügbar

    urllib3: Chunked Deflate streaming can enter an infinite loop

    urllib3 is an HTTP client library for Python. From 2.6.2 until 2.8.0, HTTPResponse.stream and HTTPResponse.read_chunked can enter an infinite loop because the Deflate decoder retains trailing bytes as unconsumed input after reaching end-of-stream and repeatedly decodes them without progress. The issue occurs when an untrusted server sends a chunked Deflate response whose decoded body exceeds a positive finite chunk size and whose encoded body has trailing bytes, specifically a response with Transfer-Encoding: chunked and Content-Encoding: deflate, content decoding enabled, and the positive finite amt=N streaming chunk size. The attack mechani

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  3. CVE-2026-97687

    Hoch · CVSS 7.6EPSS 0,21%Korrektur verfügbar

    urllib3: HTTPS proxy TLS configuration may be ignored or overridden

    urllib3 is an HTTP client library for Python. From 1.26.0 until 2.8.0, the proxy_ssl_context, proxy_assert_hostname, proxy_assert_fingerprint, ssl_context, cert_reqs, verify_mode, use_forwarding_for_https=True, and CERT_NONE configuration paths fail to remain separated because target-server TLS settings are incorrectly applied to the HTTPS proxy connection. The trigger is that an application uses an HTTPS proxy and configures target-server TLS settings that must remain separate from the proxy TLS handshake, including HTTPS forwarding with target-specific identity or credentials. Applying cert_reqs=CERT_NONE can overwrite proxy_ssl_context.ver

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  4. CVE-2026-44431

    Hoch · CVSS 8.2EPSS 0,34%Öffentlicher ExploitKorrektur verfügbar

    urllib3: Sensitive headers forwarded across origins in proxied low-level redirects

    urllib3 is an HTTP client library for Python. From 1.23 to before 2.7.0, cross-origin redirects followed from the low-level API via ProxyManager.connection_from_url().urlopen(..., assert_same_host=False) still forward these sensitive headers. This vulnerability is fixed in 2.7.0.

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  5. CVE-2026-44432

    Hoch · CVSS 8.9EPSS 0,88%Korrektur verfügbar

    urllib3: Decompression-bomb safeguards bypassed in parts of the streaming API

    urllib3 is an HTTP client library for Python. From 2.6.0 to before 2.7.0, urllib3 could decompress the whole response instead of the requested portion (1) during the second HTTPResponse.read(amt=N) call when the response was decompressed using the official Brotli library or (2) when HTTPResponse.drain_conn() was called after the response had been read and decompressed partially (compression algorithm did not matter here). These 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 decom

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  6. CVE-2026-21441

    Hoch · CVSS 8.9EPSS 2,92%Korrektur verfügbar

    urllib3 vulnerable to decompression-bomb safeguard bypass when following HTTP redirects (streaming API)

    urllib3 is an HTTP client library for Python. urllib3's streaming API 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. urllib3 can perform decoding or decompression based on the HTTP `Content-Encoding` header (e.g., `gzip`, `deflate`, `br`, or `zstd`). When using the streaming API, the library decompresses only the necessary bytes, enabling partial content consumption. Starting in version 1.22 and prior to version 2.6.3, for HTTP redirect responses, the library would read the entire response body to drain the connection and decomp

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  7. CVE-2025-66471

    Hoch · CVSS 8.9EPSS 0,68%Korrektur verfügbar

    urllib3 Streaming API improperly handles highly compressed data

    urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.0 and prior to 2.6.0, the Streaming API improperly handles highly compressed data. urllib3's streaming API 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. When streaming a compressed response, urllib3 can perform decoding or decompression based on the HTTP Content-Encoding header (e.g., gzip, deflate, br, or zstd). The library must read compressed data from the network and decompress it until the requested chunk size is met. Any resulting decompresse

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  8. CVE-2025-66418

    Hoch · CVSS 8.9EPSS 0,68%Korrektur verfügbar

    urllib3 allows an unbounded number of links in the decompression chain

    urllib3 is a user-friendly HTTP client library for Python. Starting in version 1.24 and prior to 2.6.0, the number of links in the decompression chain was unbounded allowing a malicious server to insert a virtually unlimited number of compression steps leading to high CPU usage and massive memory allocation for the decompressed data. This vulnerability is fixed in 2.6.0.

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  9. CVE-2025-50182

    Mittel · CVSS 5.3EPSS 0,39%Korrektur verfügbar

    urllib3 does not control redirects in browsers and Node.js

    urllib3 is a user-friendly HTTP client library for Python. Starting in version 2.2.0 and prior to 2.5.0, urllib3 does not control redirects in browsers and Node.js. urllib3 supports being used in a Pyodide runtime utilizing the JavaScript Fetch API or falling back on XMLHttpRequest. This means Python libraries can be used to make HTTP requests from a browser or Node.js. Additionally, urllib3 provides a mechanism to control redirects, but the retries and redirect parameters are ignored with Pyodide; the runtime itself determines redirect behavior. This issue has been patched in version 2.5.0.

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  10. CVE-2025-50181

    Mittel · CVSS 5.3EPSS 0,47%Korrektur verfügbar

    urllib3 redirects are not disabled when retries are disabled on PoolManager instantiation

    urllib3 is a user-friendly HTTP client library for Python. Prior to 2.5.0, it is possible to disable redirects for all requests by instantiating a PoolManager and specifying retries in a way that disable redirects. By default, requests and botocore users are not affected. An application attempting to mitigate SSRF or open redirect vulnerabilities by disabling redirects at the PoolManager level will remain vulnerable. This issue has been patched in version 2.5.0.

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  11. CVE-2024-37891

    Mittel · CVSS 4.4EPSS 1,14%Korrektur verfügbar

    Proxy-Authorization request header isn't stripped during cross-origin redirects in urllib3

    urllib3 is a user-friendly HTTP client library for Python. When using urllib3's proxy support with `ProxyManager`, the `Proxy-Authorization` header is only sent to the configured proxy, as expected. However, when sending HTTP requests *without* using urllib3's proxy support, it's possible to accidentally configure the `Proxy-Authorization` header even though it won't have any effect as the request is not using a forwarding proxy or a tunneling proxy. In those cases, urllib3 doesn't treat the `Proxy-Authorization` HTTP header as one carrying authentication material and thus doesn't strip the header on cross-origin redirects. Because this is a

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  12. CVE-2023-45803

    Mittel · CVSS 4.2EPSS 0,59%Korrektur verfügbar

    Request body not stripped after redirect in urllib3

    urllib3 is a user-friendly HTTP client library for Python. urllib3 previously wouldn't remove the HTTP request body when an HTTP redirect response using status 301, 302, or 303 after the request had its method changed from one that could accept a request body (like `POST`) to `GET` as is required by HTTP RFCs. Although this behavior is not specified in the section for redirects, it can be inferred by piecing together information from different sections and we have observed the behavior in other major HTTP client implementations like curl and web browsers. Because the vulnerability requires a previously trusted service to become compromised in

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  13. CVE-2018-25091

    Mittel · CVSS 6.1EPSS 0,59%Korrektur verfügbar

    CVE-2018-25091

    urllib3 before 1.24.2 does not remove the authorization HTTP header when following a cross-origin redirect (i.e., a redirect that differs in host, port, or scheme). This can allow for credentials in the authorization header to be exposed to unintended hosts or transmitted in cleartext. NOTE: this issue exists because of an incomplete fix for CVE-2018-20060 (which was case-sensitive).

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  14. CVE-2023-43804

    Mittel · CVSS 5.9EPSS 1,36%Korrektur verfügbar

    `Cookie` HTTP header isn't stripped on cross-origin redirects

    urllib3 is a user-friendly HTTP client library for Python. urllib3 doesn't treat the `Cookie` HTTP header special or provide any helpers for managing cookies over HTTP, that is the responsibility of the user. However, it is possible for a user to specify a `Cookie` header and unknowingly leak information via HTTP redirects to a different origin if that user doesn't disable redirects explicitly. This issue has been patched in urllib3 version 1.26.17 or 2.0.5.

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  15. CVE-2021-33503

    Hoch · CVSS 7.5EPSS 3,27%Korrektur verfügbar

    CVE-2021-33503

    An issue was discovered in urllib3 before 1.26.5. When provided with a URL containing many @ characters in the authority component, the authority regular expression exhibits catastrophic backtracking, causing a denial of service if a URL were passed as a parameter or redirected to via an HTTP redirect.

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  16. CVE-2021-28363

    Mittel · CVSS 6.5EPSS 2,17%Korrektur verfügbar

    CVE-2021-28363

    The urllib3 library 1.26.x before 1.26.4 for Python omits SSL certificate validation in some cases involving HTTPS to HTTPS proxies. The initial connection to the HTTPS proxy (if an SSLContext isn't given via proxy_config) doesn't verify the hostname of the certificate. This means certificates for different servers that still validate properly with the default urllib3 SSLContext will be silently accepted.

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  18. CVE-2020-7212

    Hoch · CVSS 7.5EPSS 3,37%Korrektur verfügbar

    CVE-2020-7212

    The _encode_invalid_chars function in util/url.py in the urllib3 library 1.25.2 through 1.25.7 for Python allows a denial of service (CPU consumption) because of an inefficient algorithm. The percent_encodings array contains all matches of percent encodings. It is not deduplicated. For a URL of length N, the size of percent_encodings may be up to O(N). The next step (normalize existing percent-encoded bytes) also takes up to O(N) for each step, so the total time is O(N^2). If percent_encodings were deduplicated, the time to compute _encode_invalid_chars would be O(kN), where k is at most 484 ((10+6*2)^2).

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  19. CVE-2019-11324

    Hoch · CVSS 7.5EPSS 2,92%Korrektur verfügbar

    CVE-2019-11324

    The urllib3 library before 1.24.2 for Python mishandles certain cases where the desired set of CA certificates is different from the OS store of CA certificates, which results in SSL connections succeeding in situations where a verification failure is the correct outcome. This is related to use of the ssl_context, ca_certs, or ca_certs_dir argument.

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