CVE-2026-44432
highEPSS 0.009 · 58 %ileDEEURUUSEPSS · scored 2026-10-18
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 decompressed data) on the client side. This vulnerability is fixed in 2.7.0.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.3–8.9
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (52)
Products and version ranges known to be affected.
advisories (5)
Vendor and ecosystem advisories describing this.
- WID-SEC-W-2026-1923Red Hat Ansible Automation Platform: Mehrere SchwachstellenDeutsch2026-06-14csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Red Hat Ansible Automation Platform ausnutzen, um Sicherheitsvorkehrungen zu umgehen, Informationen offenzulegen, Daten zu manipulieren und einen Denial-of-Service-Zustand herbeizuführen.
- WID-SEC-W-2026-2455Oracle Solaris Drittanbieterkomponenten: Mehrere SchwachstellenDeutsch2026-07-21csaf · cert_bundDE
Ein entfernter, anonymer oder authentisierter Angreifer kann mehrere Schwachstellen in verschiedenen Komponenten von Drittanbietern in Oracle Solaris ausnutzen, um einen nicht näher spezifizierten Angriff durchzuführen.
- WID-SEC-W-2026-3046IBM Concert: Mehrere SchwachstellenDeutsch2026-08-26csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in IBM Concert ausnutzen, um beliebigen Programmcode auszuführen, um einen Denial of Service Angriff durchzuführen, um Informationen offenzulegen, um Dateien zu manipulieren, um einen Cross-Site Scripting Angriff durchzuführen, um einen SQL-Injection Angriff durchzuführen und um Sicherheitsvorkehrungen zu umgehen.
- GHSA-mf9v-mfxr-j63jurllib3: Decompression-bomb safeguards bypassed in parts of the streaming API2026-05-11ghsa · osvUS
### Impact urllib3's [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. urllib3 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. However, urllib3 before version 2.7.0 could still decompress the whole response instead of the requested portion in two cases: 1. During the second `HTTPResponse.read(amt=N)` call when the response was decompressed using the official [Brotli](https://pypi.org/project/brotli/) library. 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 decompressed data; CWE-409) on the client side. ### Affected usages Applications 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: 1. 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. 2. `HTTPResponse.drain_conn()` is called after response decompression has already started. ### Remediation Upgrade to at least urllib3 version 2.7.0 in which the library: 1. Is more efficient for reads with Brotli. 2. Always skips decompression for `HTTPResponse.drain_conn()`. If upgrading is not immediately possible, the following workarounds may reduce exposure in specific cases: 1. 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. 2. If your code explicitly calls `HTTPResponse.drain_conn()`, call `HTTPResponse.close()` instead when connection reuse is not important. ### Credits The Brotli-specific issue was reported by @kimkou2024. `HTTPResponse.drain_conn()` inefficiency was reported by @Cycloctane.
- PYSEC-2026-1422026-05-13vendor · osvUS
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 decompressed data) on the client side. This vulnerability is fixed in 2.7.0.
also known as (7)
Other names and identifiers for this entity.
sources
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references (65)
External citations — patches, advisories, analysis.
- https://github.com/urllib3/urllib3/releasesPatchcnnvd
- https://nvd.nist.gov/vuln/detail/CVE-2026-44432cnnvd
- https://github.com/urllib3/urllib3/security/advisories/GHSA-mf9v-mfxr-j63jenisa_euvd
- https://access.redhat.com/errata/RHSA-2026:15862nvd
- https://access.redhat.com/errata/RHSA-2026:20338nvd
- https://access.redhat.com/errata/RHSA-2026:22934nvd
- https://access.redhat.com/errata/RHSA-2026:24000nvd
- https://access.redhat.com/errata/RHSA-2026:24009nvd
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