CVE-2023-41909 in FRR
Summary
by MITRE • 09/05/2023
An issue was discovered in FRRouting FRR through 9.0. bgp_nlri_parse_flowspec in bgpd/bgp_flowspec.c processes malformed requests with no attributes, leading to a NULL pointer dereference.
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Analysis
by VulDB Data Team • 12/12/2024
The vulnerability identified as CVE-2023-41909 affects FRRouting FRR versions up to and including 9.0, specifically within the border gateway protocol implementation. This flaw resides in the bgp_nlri_parse_flowspec function located in the bgpd/bgp_flowspec.c source file, representing a critical security weakness that can compromise network infrastructure integrity. The issue manifests when the system processes malformed BGP flowspec requests that lack proper attribute validation, creating a scenario where the software attempts to dereference a null pointer during processing.
The technical implementation of this vulnerability stems from inadequate input validation within the BGP flowspec parsing mechanism. When malformed requests are received without essential attributes, the bgp_nlri_parse_flowspec function fails to properly handle the absence of expected data structures, resulting in a NULL pointer dereference condition. This type of error typically occurs when software assumes certain memory locations contain valid data without proper verification, a pattern commonly associated with CWE-476 Null Pointer Dereference. The flaw essentially creates a path where the program attempts to access memory at address zero or an invalid location, causing a crash or potential exploitation vector.
The operational impact of CVE-2023-41909 extends beyond simple system instability, potentially affecting network availability and stability in environments relying on FRRouting for BGP operations. Network devices running affected versions may experience unexpected termination or restarts when processing malformed flowspec requests, leading to routing disruptions that could affect traffic flow across the network. This vulnerability aligns with ATT&CK technique T1499.004 Network Denial of Service, as it can be exploited to create service interruptions through carefully crafted BGP messages. The disruption could be particularly severe in large network infrastructures where BGP flowspec functionality is actively used for traffic filtering and policy enforcement.
Mitigation strategies for this vulnerability require immediate patching of affected FRRouting installations to versions that address the NULL pointer dereference issue. Network administrators should also implement additional monitoring and filtering mechanisms to detect and prevent malformed BGP flowspec requests from reaching vulnerable systems. The fix typically involves adding proper null checks and validation before attempting to access memory locations, ensuring that the software gracefully handles malformed input rather than crashing. Organizations should also consider implementing network segmentation and access controls to limit exposure, while maintaining regular vulnerability assessments to identify potential similar issues in other network protocols and components. The remediation process should include thorough testing to ensure that the patch does not introduce regressions in legitimate BGP flowspec functionality while effectively addressing the null pointer dereference condition.