CVE-2026-73568: CWE-400: Uncontrolled Resource Consumption in libp2p py-libp2p
py-libp2p is the Python implementation of the libp2p networking stack. In 0.7.0 and earlier, the yamux handle_incoming() method in libp2p/stream_muxer/yamux/yamux.py reads an attacker-controlled 32-bit DATA frame length with read_exactly() before validating it against MAX_WINDOW_SIZE or checking whether stream_id exists. A peer that completes the standard Noise handshake can send a 12-byte frame declaring a 0xFFFFFFFF body and then withhold the body, causing the sequential yamux read loop used by the default new_host() configuration to block and preventing every stream on that connection from making progress. No fixed version is available as of this review.
AI Analysis
Technical Summary
In py-libp2p versions before 0.7.1, the yamux handle_incoming() method reads a 32-bit DATA frame length from an attacker-controlled source without validating it against MAX_WINDOW_SIZE or verifying the existence of the stream_id. An attacker who completes the Noise handshake can send a 12-byte frame declaring a 0xFFFFFFFF body length and then withhold the body, causing the sequential yamux read loop to block indefinitely. This results in uncontrolled resource consumption and denial of service affecting all streams on the connection. No patch or official remediation is available at this time.
Potential Impact
An unauthenticated remote attacker can cause a denial of service by blocking the yamux read loop, preventing any stream on the connection from making progress. This leads to resource exhaustion and disruption of network communication using py-libp2p prior to version 0.7.1. Confidentiality and integrity are not impacted.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, consider limiting exposure to untrusted peers or implementing network-level controls to detect and block malformed frames.
CVE-2026-73568: CWE-400: Uncontrolled Resource Consumption in libp2p py-libp2p
Description
py-libp2p is the Python implementation of the libp2p networking stack. In 0.7.0 and earlier, the yamux handle_incoming() method in libp2p/stream_muxer/yamux/yamux.py reads an attacker-controlled 32-bit DATA frame length with read_exactly() before validating it against MAX_WINDOW_SIZE or checking whether stream_id exists. A peer that completes the standard Noise handshake can send a 12-byte frame declaring a 0xFFFFFFFF body and then withhold the body, causing the sequential yamux read loop used by the default new_host() configuration to block and preventing every stream on that connection from making progress. No fixed version is available as of this review.
CVSS v3.1
Score 7.5high
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
In py-libp2p versions before 0.7.1, the yamux handle_incoming() method reads a 32-bit DATA frame length from an attacker-controlled source without validating it against MAX_WINDOW_SIZE or verifying the existence of the stream_id. An attacker who completes the Noise handshake can send a 12-byte frame declaring a 0xFFFFFFFF body length and then withhold the body, causing the sequential yamux read loop to block indefinitely. This results in uncontrolled resource consumption and denial of service affecting all streams on the connection. No patch or official remediation is available at this time.
Potential Impact
An unauthenticated remote attacker can cause a denial of service by blocking the yamux read loop, preventing any stream on the connection from making progress. This leads to resource exhaustion and disruption of network communication using py-libp2p prior to version 0.7.1. Confidentiality and integrity are not impacted.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, consider limiting exposure to untrusted peers or implementing network-level controls to detect and block malformed frames.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-12T20:53:46.381Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a7e058ebf8831d539950102
Added to database: 08/13/2026, 17:57:34 UTC
Last enriched: 08/13/2026, 18:11:08 UTC
Last updated: 08/13/2026, 18:41:55 UTC
Views: 3
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