https://feed.craftedsignal.io/tags/frrouting/Trending threats, MITRE ATT&CK coverage, and detection metadata. Fed continuously.Hugoenhello@craftedsignal.iohello@craftedsignal.ioTue, 19 May 2026 07:13:46 +0000https://feed.craftedsignal.io/briefs/2026-05-frr-bgp-dos/Tue, 19 May 2026 07:13:46 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2026-05-frr-bgp-dos/An integer underflow vulnerability, CVE-2026-37459, in FRRouting (FRR) versions stable/10.0 to stable/10.6 allows a remote attacker to cause a Denial of Service (DoS) by sending a crafted BGP UPDATE message.CVE-2026-37459 is an integer underflow vulnerability affecting FRRouting (FRR), a widely used IP routing protocol suite for Linux and Unix platforms. The vulnerability resides in the BGP (Border Gateway Protocol) UPDATE message processing logic within FRR versions stable/10.0 to stable/10.6. A remote attacker can exploit this flaw by sending a specially crafted BGP UPDATE message to a vulnerable FRR instance, triggering an integer underflow. This underflow condition can lead to memory corruption or other unexpected behavior, ultimately causing the FRR process to crash and resulting in a Denial of Service (DoS) condition. This vulnerability poses a risk to network availability, as it can disrupt routing operations and impact network connectivity.

Attack Chain

1. Attacker identifies a vulnerable FRR instance running a version between stable/10.0 and stable/10.6.
2. Attacker crafts a malicious BGP UPDATE message designed to trigger the integer underflow. The specific details of the message structure are not available in the provided source.
3. Attacker sends the crafted BGP UPDATE message to the vulnerable FRR instance over TCP port 179, the standard BGP port.
4. The FRR instance receives the BGP UPDATE message and begins processing it.
5. During the processing of the BGP UPDATE message, the integer underflow occurs due to a calculation error.
6. The integer underflow leads to memory corruption within the FRR process.
7. The memory corruption causes the FRR process to crash.
8. The crash of the FRR process results in a Denial of Service (DoS), disrupting routing operations.

Impact

Successful exploitation of CVE-2026-37459 can lead to a Denial of Service (DoS) condition, impacting the availability of network routing services. While the exact number of affected organizations is unknown, FRR is used in a variety of network environments, including enterprise networks, service provider networks, and research networks. A successful attack could disrupt routing operations, leading to network outages, service disruptions, and potential financial losses.

Recommendation

• Upgrade FRRouting (FRR) to a patched version beyond stable/10.6 to remediate CVE-2026-37459.
• Monitor network traffic for suspicious BGP UPDATE messages that may indicate exploitation attempts using the “Detect Suspicious BGP UPDATE Messages” Sigma rule.
• Implement rate limiting for BGP UPDATE messages to mitigate the impact of a DoS attack.

]]>mediumadvisorybgpdosfrroutingnetworkhttps://feed.craftedsignal.io/briefs/2026-05-frrouting-dos/Tue, 19 May 2026 07:13:08 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2026-05-frrouting-dos/A denial-of-service vulnerability, identified as CVE-2026-37458, exists in the MP_REACH_NLRI component of FRRouting versions stable/10.0 to stable/10.6, where authenticated attackers can trigger a DoS by sending a crafted UPDATE message due to missing input validation.FRRouting (FRR) is susceptible to a denial-of-service (DoS) vulnerability, tracked as CVE-2026-37458, affecting versions stable/10.0 through stable/10.6. The vulnerability lies within the MP_REACH_NLRI component and stems from a lack of input validation when processing UPDATE messages. An authenticated attacker can exploit this flaw by sending a specially crafted UPDATE message, leading to resource exhaustion or service interruption on the affected FRR instance. Successful exploitation can disrupt network routing and availability. Defenders should apply the appropriate patches or mitigations to prevent potential exploitation.

Attack Chain

1. An authenticated attacker gains network access to an FRR instance running a vulnerable version (stable/10.0 to stable/10.6).
2. The attacker crafts a malicious BGP UPDATE message specifically targeting the MP_REACH_NLRI component.
3. This crafted UPDATE message contains invalid or oversized data within the NLRI (Network Layer Reachability Information) fields.
4. The attacker sends the crafted UPDATE message to the targeted FRR instance.
5. The FRR instance receives the crafted UPDATE message and attempts to process the malformed NLRI data.
6. Due to the missing input validation, the FRR instance consumes excessive resources (CPU, memory) while processing the invalid NLRI.
7. The resource exhaustion leads to a denial of service, impacting the routing functionality of the FRR instance.

Impact

Successful exploitation of CVE-2026-37458 results in a denial-of-service condition, preventing the FRRouting instance from properly functioning. This can disrupt network routing, leading to connectivity issues and potential network outages. The impact is primarily a loss of availability for network services relying on the affected FRR instance. The number of potential victims depends on the deployment size of FRRouting within an organization’s network infrastructure.

Recommendation

• Upgrade FRRouting instances to a patched version beyond stable/10.6 to remediate CVE-2026-37458.
• Deploy the Sigma rule “Detect CVE-2026-37458 Exploitation Attempt - Malformed BGP UPDATE Message” to identify suspicious BGP UPDATE messages indicative of exploitation attempts.
• Implement rate limiting for BGP UPDATE messages to mitigate the impact of potential DoS attacks.
• Monitor network traffic for unusual patterns related to BGP UPDATE messages.

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