CVE-2026-44431 — urllib3: Sensitive headers forwarded across origins in proxied low-level redirects

Affected: urllib3

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.

GHSA-65pc-fj4g-8rjx — Internationalized Domain Names in Applications (IDNA): Specially crafted inputs to idna.encode() can bypass CVE-2024-36…

Affected: PyPI: idna

This is the same issue as CVE-2024-3651, however the original remediation in 2024 was not a complete fix. Payloads such as `"\u0660" * N` or `"\u30fb" * N + "\u6f22"` utilize the `valid_contexto` function prior to length rejection, and for high values of `N` will take a long time to process.

### Impact A specially crafted argument to the `idna.encode()` function could consume significant resources. This may lead to a denial-of-service.

### Patches Starting in version 3.14, the function rejects long inputs as soon as practicable prior to any further processing to minimize resource consumption. In version 3.15, this approach was extended to lesser used alternate functions (i.e. per-label conversions and codec support).

### Workarounds Domain names cannot exceed 253 characters in length, if this length limit is enforced prior to passing the domain to the `idna.encode()` function it should no longer consume significant resources. This is triggered by arbitrarily large inputs that would not occur in normal usage, but may be passed to the library assuming there is no preliminary input validation by the higher-level application.

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CVE-2026-44431 — urllib3: Sensitive headers forwarded across origins in proxied low-level redirects

GHSA-65pc-fj4g-8rjx — Internationalized Domain Names in Applications (IDNA): Specially crafted inputs to idna.encode() can bypass CVE-2024-36…