CVE-2025-49140: Pion Interceptor DoS Vulnerability

CVE-2025-49140 Overview

CVE-2025-49140 is a Denial of Service (DoS) vulnerability affecting Pion Interceptor, a popular Go framework used for building RTP/RTCP communication software. The vulnerability exists in the RTP packet factory component, where crafted RTP packets can trigger a panic condition in Pion-based Selective Forwarding Units (SFUs). This flaw allows unauthenticated remote attackers to crash WebRTC applications by sending maliciously crafted RTP packets over the network.

Critical Impact

Remote attackers can cause application crashes in WebRTC communication systems by sending crafted RTP packets with invalid padding values, potentially disrupting real-time audio/video communications.

Affected Products

• Pion Interceptor v0.1.36
• Pion Interceptor v0.1.37
• Pion Interceptor v0.1.38

Discovery Timeline

• 2025-06-09 - CVE-2025-49140 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-49140

Vulnerability Analysis

The vulnerability stems from improper resource allocation handling (CWE-770) in the RTP packet factory component of Pion Interceptor. The flaw occurs when processing RTP packets with the padding bit (P-bit) set. The vulnerable code fails to properly validate the padding length value against the actual payload size, leading to an uncontrolled panic when the padding length is either zero or exceeds the remaining payload length.

When an RTP packet is received with the P-bit set, the last byte of the payload indicates the padding length. The vulnerable implementation did not check whether this padding length value was valid before processing, allowing attackers to craft packets that trigger integer overflow conditions or out-of-bounds access attempts, resulting in a Go panic that crashes the application.

Root Cause

The root cause is insufficient input validation in the PacketFactory component within internal/rtpbuffer/packet_factory.go. The code failed to verify that the padding length (padLen) satisfies the constraint padLen > 0 && padLen <= payloadLength before processing the RTP packet payload. This missing boundary check allows malformed packets to cause a panic condition when the padding calculation results in an overflow.

Attack Vector

An attacker can exploit this vulnerability remotely over the network without requiring any authentication or user interaction. The attack involves:

1. Establishing an RTP session with a vulnerable Pion-based SFU
2. Sending crafted RTP packets with the P-bit (padding) flag set
3. Setting the padding length byte to either zero or a value larger than the actual payload size
4. The packet factory processes the malformed packet and panics due to the invalid padding value

The patch introduces proper validation and error handling:

// Error definition added for padding overflow detection
// Source: internal/rtpbuffer/errors.go
	errPacketReleased          = errors.New("could not retain packet, already released")
	errFailedToCastHeaderPool  = errors.New("could not access header pool, failed cast")
	errFailedToCastPayloadPool = errors.New("could not access payload pool, failed cast")
+	errPaddingOverflow         = errors.New("padding size exceeds payload size")
)

Source: GitHub Commit

Detection Methods for CVE-2025-49140

Indicators of Compromise

• Unexpected application crashes or restarts of Pion-based WebRTC services
• Panic logs referencing internal/rtpbuffer/packet_factory.go or padding-related operations
• Unusual RTP packet patterns with P-bit set but abnormal payload sizes
• Increased error rates in RTP/RTCP communication streams

Detection Strategies

• Monitor application logs for Go panic stack traces originating from the pion/interceptor package
• Implement network traffic analysis to detect RTP packets with suspicious padding configurations
• Deploy intrusion detection rules to flag RTP packets where the padding byte value exceeds normal bounds
• Enable SentinelOne Singularity XDR to detect crash patterns and anomalous process behavior

Monitoring Recommendations

• Configure alerting on WebRTC service crashes and automatic restarts
• Implement RTP-level packet inspection at network boundaries when feasible
• Monitor for repeated connection attempts from the same source following service disruptions
• Track application uptime metrics for Pion-based services to detect exploitation attempts

How to Mitigate CVE-2025-49140

Immediate Actions Required

• Upgrade Pion Interceptor to version v0.1.39 or later immediately
• Review all applications using pion/interceptor to identify vulnerable deployments
• Implement rate limiting on RTP streams to reduce the impact of potential attacks
• Consider deploying a reverse proxy or RTP-aware firewall to filter malformed packets

Patch Information

The vulnerability has been fixed in Pion Interceptor version v0.1.39. The patch adds proper validation to ensure that padLen > 0 && padLen <= payloadLength before processing RTP packets, and returns an error on overflow conditions instead of panicking. Users should upgrade by updating their Go module dependencies:

The fix was implemented via Pull Request #338 and the security advisory is available at the GitHub Security Advisory. Additional context can be found in the related issue discussion.

Workarounds

• If upgrading is not immediately possible, manually apply the patch from Pull Request #338
• Implement packet filtering to drop RTP packets where the P-bit is set but the padding length is zero or exceeds the payload size
• Deploy network-level controls to restrict RTP traffic to trusted sources only
• Consider temporarily disabling padding processing if your application does not require RTP padding support

# Update Go module to patched version
go get github.com/pion/interceptor@v0.1.39
go mod tidy