Illia Volochii discovered that urllib3 did not limit the steps in a decompression chain. An attacker could possibly use this issue to cause urllib3 to use excessive resources, causing a denial of service. ( CVE-2025-66418 ) Rui Xi discovered that urllib3 incorrectly handled highly compressed data. An attacker could possibly use this issue to cause urllib3 to use excessive resources, causing a denial of service. This issue only affected Ubuntu 24.04 LTS, Ubuntu 25.04, and Ubuntu 25.10. ( CVE-2025-66471 ) For the brotli encoding, the fix for CVE-2025-66471 requires an additional security update in the brotli package.
Illia Volochii discovered that urllib3 did not limit the steps in a decompression chain. An attacker could possibly use this issue to cause urllib3 to use excessive resources, causing a denial of service. ( CVE-2025-66418 )
Rui Xi discovered that urllib3 incorrectly handled highly compressed data. An attacker could possibly use this issue to cause urllib3 to use excessive resources, causing a denial of service. This issue only affected Ubuntu 24.04 LTS, Ubuntu 25.04, and Ubuntu 25.10. ( CVE-2025-66471 )
For the brotli encoding, the fix for CVE-2025-66471 requires an additional security update in the brotli package.
Illia Volochii discovered that urllib3 did not limit the steps in a decompression chain. An attacker could possibly use this issue to cause urllib3 to use excessive resources, causing a denial of service. ( CVE-2025-66418 ) Rui Xi discovered that urllib3 incorrectly handled highly compressed data. An attacker could possibly use this issue to cause urllib3 to use excessive resources, causing a denial of service. This issue only affected Ubuntu 24.04 LTS, Ubuntu 25.04, and Ubuntu 25.10. ( CVE-2025-66471 ) For the brotli encoding, the fix for CVE-2025-66471 requires an additional security update in the brotli package.
Illia Volochii discovered that urllib3 did not limit the steps in a decompression chain. An attacker could possibly use this issue to cause urllib3 to use excessive resources, causing a denial of service. ( CVE-2025-66418 )
Rui Xi discovered that urllib3 incorrectly handled highly compressed data. An attacker could possibly use this issue to cause urllib3 to use excessive resources, causing a denial of service. This issue only affected Ubuntu 24.04 LTS, Ubuntu 25.04, and Ubuntu 25.10. ( CVE-2025-66471 )
For the brotli encoding, the fix for CVE-2025-66471 requires an additional security update in the brotli package.
In general, a standard system update will make all the necessary changes.
The problem can be corrected by updating your system to the following package versions:
Ubuntu Pro provides ten-year security coverage to 25,000+ packages in Main and Universe repositories, and it is free for up to five machines.
The full story
This article is one source in a clustered incident — the cluster page carries the summary, timeline and every other outlet covering it.
