Distribution advisory
This page covers CVE-2025-66471 as tracked by Alpine, for the package py3-urllib3. The fix is available in version 2.6.3-r0; earlier versions remain affected.
How this vulnerability can be exploited
This issue can be reached over the network, attack complexity is low, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity none, availability high.
CVSS metrics in full
The score comes from this vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Attack vector: Network — reachable from anywhere that can route to the service.
- Attack complexity: Low — the attack works reliably, with no preparation.
- Privileges required: None — an unauthenticated stranger can try it.
- User interaction: None — nobody has to be tricked into anything.
- Scope: Unchanged — the damage stays inside the vulnerable component.
- Confidentiality impact: None.
- Integrity impact: None.
- Availability impact: High — total loss, or loss the attacker controls.
Weakness class
ALPINE-CVE-2025-66471 is classified as CWE-409: Improper Handling of Highly Compressed Data (Data Amplification). The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output.
Affected software
ALPINE-CVE-2025-66471 is recorded against 1 package.
- py3-urllib3 (fixed in 2.6.3-r0)
Timeline and source
Published on 5 December 2025 and last revised on 15 June 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.
References
security.alpinelinux.org (Advisory)
Other advisories for this package
py3-urllib3 has other advisories on record. If you are patching this one, these are worth checking on the same host:
Same weakness in other software
These advisories are the same class of weakness (CWE-409: Improper Handling of Highly Compressed Data (Data Amplification)) in other software:
