Cloudflare: >> Quiche >> 0.9.0 Security Vulnerabilities
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 exercising an opportunistic ACK attack; see RFC 9000 Section 21.4. The victim could grow the congestion window beyond typical expectations and allow more bytes in flight than the path might really support.
Patches
quiche 0.24.4 is the earliest version containing the fix for this issue.
CVSS Score
5.3
EPSS Score
0.001
Published
2025-06-18
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.
CVSS Score
7.5
EPSS Score
0.001
Published
2025-06-18
Cloudflare quiche was discovered to be vulnerable to unbounded storage of information related to connection ID retirement, which could lead to excessive resource consumption. Each QUIC connection possesses a set of connection Identifiers (IDs); see RFC 9000 Section 5.1 https://datatracker.ietf.org/doc/html/rfc9000#section-5.1 . Endpoints declare the number of active connection IDs they are willing to support using the active_connection_id_limit transport parameter. The peer can create new IDs using a NEW_CONNECTION_ID frame but must stay within the active ID limit. This is done by retirement of old IDs, the endpoint sends NEW_CONNECTION_ID includes a value in the retire_prior_to field, which elicits a RETIRE_CONNECTION_ID frame as confirmation. An unauthenticated remote attacker can exploit the vulnerability by sending NEW_CONNECTION_ID frames and manipulating the connection (e.g. by restricting the peer's congestion window size) so that RETIRE_CONNECTION_ID frames can only be sent at a slower rate than they are received, leading to storage of information related to connection IDs in an unbounded queue. Quiche versions 0.19.2 and 0.20.1 are the earliest to address this problem. There is no workaround for affected versions.
CVSS Score
3.7
EPSS Score
0.004
Published
2024-03-12
Cloudflare Quiche (through version 0.19.1/0.20.0) was affected by an unlimited resource allocation vulnerability causing rapid increase of memory usage of the system running quiche server or client.
A remote attacker could take advantage of this vulnerability by repeatedly sending an unlimited number of 1-RTT CRYPTO frames after previously completing the QUIC handshake.
Exploitation was possible for the duration of the connection which could be extended by the attacker.
quiche 0.19.2 and 0.20.1 are the earliest versions containing the fix for this issue.
CVSS Score
5.9
EPSS Score
0.025
Published
2024-03-12