CVE-2025-4821
June 18, 2025
Impact
Cloudflare quiche was discovered to be vulnerable to incorrect congestion window growth, which could cause it to send data at a rate faster than the path might actually support.
An unauthenticated remote attacker can exploit the vulnerability by first completing a handshake and initiating a congestion-controlled data transfer towards itself. Then, it could manipulate the victim's congestion control state by sending ACK frames covering a large range of packet numbers (including packet numbers that had never been sent); see RFC 9000 Section 19.3. The victim could grow the congestion window beyond typical expectations and allow more bytes in flight than the path might really support. In extreme cases, the window might grow beyond the limit of the internal variable's type, leading to an overflow panic.
Patches
quiche 0.24.4 is the earliest version containing the fix for this issue.
Affected Packages
https://github.com/cloudflare/quiche.git (GITHUB):
Affected version(s) >=0.1.0 <0.24.4Fix Suggestion:
Update to version 0.24.4quiche (RUST):
Affected version(s) >=0.1.0-alpha1 <0.24.4Fix Suggestion:
Update to version 0.24.4Additional Notes
The description of this vulnerability differs from MITRE.
Related Resources (1)
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Contact UsCVSS v4
Base Score:
8.7
Attack Vector
NETWORK
Attack Complexity
LOW
Attack Requirements
NONE
Privileges Required
NONE
User Interaction
NONE
Vulnerable System Confidentiality
NONE
Vulnerable System Integrity
NONE
Vulnerable System Availability
HIGH
Subsequent System Confidentiality
NONE
Subsequent System Integrity
NONE
Subsequent System Availability
NONE
CVSS v3
Base Score:
7.5
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Weakness Type (CWE)
Allocation of Resources Without Limits or Throttling
EPSS
Base Score:
0.24