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2 vulnerabilities found for urllib3/urllib3 by urllib3
CVE-2026-9375 (GCVE-0-2026-9375)
Vulnerability from nvd – Published: 2026-06-19 18:45 – Updated: 2026-06-22 15:53
VLAI
EPSS
VEX
Title
Decompression Bomb Bypass via Negative max_length in Streaming API in urllib3
Summary
urllib3 version 2.6.3 is vulnerable to a decompression bomb bypass in its streaming API (`preload_content=False`) when using Brotli support. The issue arises due to three independent code paths in `response.py` that bypass the `max_length` protection introduced in version 2.6.0 to mitigate CVE-2025-66471. Specifically, negative `max_length` values can be produced due to buffer arithmetic in `read()`, `flush_decoder` unconditionally overrides `max_length` to `-1`, and `_flush_decoder()` passes no limit at all, defaulting to unlimited decompression. This allows a malicious HTTP server to trigger an out-of-memory (OOM) condition by decompressing large payloads into memory, leading to a denial of service (DoS). The vulnerability affects urllib3 2.6.3 and Brotli 1.2.0 and impacts applications and libraries using `requests` or `urllib3` to stream content from untrusted sources.
Severity
7.5 (High)
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-400 - Uncontrolled Resource Consumption
Assigner
References
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| urllib3 | urllib3/urllib3 |
Affected:
unspecified , < 2.7.0
(custom)
|
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CVE-2026-9375 (GCVE-0-2026-9375)
Vulnerability from cvelistv5 – Published: 2026-06-19 18:45 – Updated: 2026-06-22 15:53
VLAI
EPSS
VEX
Title
Decompression Bomb Bypass via Negative max_length in Streaming API in urllib3
Summary
urllib3 version 2.6.3 is vulnerable to a decompression bomb bypass in its streaming API (`preload_content=False`) when using Brotli support. The issue arises due to three independent code paths in `response.py` that bypass the `max_length` protection introduced in version 2.6.0 to mitigate CVE-2025-66471. Specifically, negative `max_length` values can be produced due to buffer arithmetic in `read()`, `flush_decoder` unconditionally overrides `max_length` to `-1`, and `_flush_decoder()` passes no limit at all, defaulting to unlimited decompression. This allows a malicious HTTP server to trigger an out-of-memory (OOM) condition by decompressing large payloads into memory, leading to a denial of service (DoS). The vulnerability affects urllib3 2.6.3 and Brotli 1.2.0 and impacts applications and libraries using `requests` or `urllib3` to stream content from untrusted sources.
Severity
7.5 (High)
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
- CWE-400 - Uncontrolled Resource Consumption
Assigner
References
Impacted products
1 product
| Vendor | Product | Version | |
|---|---|---|---|
| urllib3 | urllib3/urllib3 |
Affected:
unspecified , < 2.7.0
(custom)
|
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