CVE-2026-88411

Executive Summary

CVE-2026-88411 is a high-severity (CVSS 7.5) denial-of-service vulnerability in FalkorDB, a Redis module implementing a graph database. The flaw stems from improper error handling in the GRAPH.EFFECT command handler, specifically within the /effects/effects_apply.c source file, allowing an unauthenticated remote attacker to crash or destabilize the FalkorDB service. Organizations running FalkorDB v4.20.1 are affected; exploitation requires only network reachability to the Redis/FalkorDB listener, with no authentication or user interaction.

Technical Analysis

FalkorDB is a graph database built as a Redis module, exposing graph operations through Redis command extensions such as GRAPH.EFFECT. CVE-2026-88411 is classified under CWE-755 (Improper Handling of Exceptional Conditions), meaning the code in /effects/effects_apply.c fails to gracefully handle an error or malformed input condition encountered during the execution of the GRAPH.EFFECT operation.

The vulnerability is reachable over the network (CVSS AV:N) with low attack complexity (AC:L), requires no privileges (PR:N) and no user interaction (UI:N). The sole impacted security property is availability (A:H), consistent with a denial-of-service outcome. Improper error handling in this context typically manifests when an operation encounters an unexpected state — for example, a null dereference, an unhandled return code, an assertion failure, or an uncaught exception path — that the component does not recover from, causing the hosting process (the Redis instance with the FalkorDB module loaded) to abort, restart, or become unresponsive.

Because FalkorDB operates in-process with Redis, a fault that terminates or stalls the hosting Redis server can affect all tenants and all graph data served by that instance, not merely the requesting client. Insufficient technical detail is available in the provided description to identify the exact error condition or the precise malformed GRAPH.EFFECT argument that triggers the fault; the analysis is therefore confined to the vulnerability class (DoS via improper error handling) and its attack surface (the network-exposed GRAPH.EFFECT command handler).

Exploitation Scenarios

No public PoC, exploit code, or Nuclei template is available for this CVE. The attack chain below is inferred from the vulnerability class (denial of service via improper error handling) and the documented attack surface (the GRAPH.EFFECT component in /effects/effects_apply.c). Specific triggering arguments cannot be derived from the available data.

1. Reconnaissance / target identification. An attacker scans for network-exposed FalkorDB instances. FalkorDB is a Redis module, so exposure is typically on the Redis default port (6379/TCP) or a custom configured port. Shodan and similar engines can identify instances via the Redis banner and FalkorDB-specific GRAPH.* command support. No authentication is required (PR:N), so any reachable instance is a candidate target.

2. Triggering the flaw class. The attacker issues a GRAPH.EFFECT command crafted to reach the vulnerable error-handling path in /effects/effects_apply.c. Because the defect resides in improper handling of exceptional conditions, the malformed or edge-case input drives the handler into an error state it does not recover from. The exact input structure is not documented in the available intelligence.

3. Payload / execution method. The attack is a single (or minimal) command sent to the FalkorDB/Redis listener over the network protocol. No authentication bypass, credential theft, or code execution is required — the request itself induces the fault in the command handler. No public payload is available; the triggering request must be reconstructed by the attacker through fuzzing or source review of the affected component.

4. Post-exploitation impact. The expected result is termination or unresponsiveness of the FalkorDB/Redis process (denial of service). Depending on configuration and supervisor behavior, the process may restart, causing repeated outages if the attacker re-sends the triggering command. The scope is confined to availability (C:N/I:N/A:H) — there is no documented confidentiality or integrity impact.

Impact Assessment

CVSS subscores: AV:N (network-reachable) / AC:L (low complexity, no special conditions) / PR:N (no authentication needed) / UI:N (no user interaction) / S:U (scope unchanged) / C:N / I:N / A:H (high availability impact). Base score 7.5, HIGH severity.

Business impact. A successful exploit denies access to the graph database, disrupting any application that depends on FalkorDB for query serving, dependency resolution, recommendation, fraud-graph, or knowledge-graph workloads. Because FalkorDB runs inside Redis, a crash can take down the entire Redis instance and all co-located data structures, amplifying blast radius beyond a single logical graph.

Blast radius. Any single network-reachable FalkorDB v4.20.1 deployment is at risk. There is no authentication barrier, so the exposed listener constitutes the full attack surface. Multi-tenant instances may affect all tenants simultaneously. There is no current evidence of exploit-in-the-wild activity, CISA KEV listing, or EPSS scoring; EPSS is not yet assigned by FIRST.org.

Detection Guidance

Sigma Rule

title: FalkorDB GRAPH.EFFECT Denial of Service Attempt (CVE-2026-88411)
id: 9b0f2c74-3a1e-4d55-8c21-7e6a4c9f1d02
status: experimental
description: Detects crash/restart indicators associated with malformed GRAPH.EFFECT commands against FalkorDB v4.20.1
author: valtersit.com
logsource:
  product: linux
  service: syslog
detection:
  selection_crash:
    - 'FalkorDB*segfault*'
    - '*effects_apply.c*'
    - '*GRAPH.EFFECT*'
  selection_redis:
    - 'Redis*crash*'
    - '*module*falkordb*abort*'
  condition: selection_crash or selection_redis
falsepositives:
  - Legitimate GRAPH.EFFECT usage
  - Operator-triggered Redis restarts
level: high

YARA Rule

rule CVE_2026_88411_FalkorDB_GraphEffect_DoS
{
    meta:
        description = "Detects GRAPH.EFFECT input patterns associated with CVE-2026-88411 in FalkorDB logs and effect traces"
        author = "valtersit.com"
        reference = "CVE-2026-88411"
        date = "2026-01-01"
        severity = "high"

    strings:
        $graph_effect = "GRAPH.EFFECT" ascii nocase
        $src_file     = "effects_apply.c" ascii
        $dofault      = "segmentation fault" ascii nocase
        $abort        = "Assertion" ascii
        $redis        = "redis" ascii nocase

    condition:
        (uint16(0) == 0x5A4D) or
        (uint32(0) == 0x464C457F) or
        $graph_effect and (#graph_effect > 0 and ($src_file or $dofault or $abort))
}

Suricata IDS Rule

alert tcp $EXTERNAL_NET any -> $HOME_NET 6379 (msg:"CVE-2026-88411 FalkorDB GRAPH.EFFECT Denial of Service Attempt"; flow:to_server,established; content:"GRAPH.EFFECT"; nocase; threshold:type threshold, track by_src, count 5, seconds 10; reference:cve,CVE-2026-88411; classtype:attempted-dos; sid:90088411; rev:1;)

Elastic Detection

sequence by process.pid with maxspan=30s
  [process where event.action == "start" and process.name == "redis-server"]
  [process where event.action == "end" and process.name == "redis-server" and process.exit_code != 0]
  [process where event.action == "start" and process.name == "redis-server"]

Splunk SPL Query

index=linux (process_name="redis-server" OR source="falkordb*")
| search "GRAPH.EFFECT" OR "effects_apply.c" OR "segfault" OR "SIGABRT"
| stats count min(_time) as first_seen max(_time) as last_seen by host, process_name, message
| where count > 0
| convert ctime(first_seen) ctime(last_seen)

Wazuh OSSEC Rule

<group name="falkordb,cve-2026-88411,">
  <rule id="884110" level="12">
    <decoded_as>syslog</decoded_as>
    <match>GRAPH.EFFECT|effects_apply.c</match>
    <description>CVE-2026-88411: Suspicious GRAPH.EFFECT activity against FalkorDB (potential DoS trigger)</description>
    <mitre>
      <id>T1499</id>
    </mitre>
  </rule>
  <rule id="884111" level="14">
    <decoded_as>syslog</decoded_as>
    <match>redis-server.*(segfault|SIGABRT|SIGSEGV|crashed)</match>
    <description>CVE-2026-88411: FalkorDB/Redis process crash detected possibly due to GRAPH.EFFECT DoS</description>
    <mitre>
      <id>T1499</id>
    </mitre>
  </rule>
</group>

Mitigation & Patch Guidance

Patch confidence: 0/4 (UNPATCHED — no patch evidence from any tracked source). No vendor fix or workaround has been published.

1) Immediate mitigations

• Restrict network exposure of the FalkorDB/Redis listener. Bind to localhost or a trusted internal interface only; never expose port 6379 to the public internet.
• Enforce network ACLs/firewalls so that only authorized application hosts may reach the FalkorDB port.
• Enable authentication (requirepass) and Redis ACLs as compensating controls, even though the vulnerability is unauthenticated-accessible by default.
• Apply Redis process supervision (systemd Restart= policy) to limit downtime, and alert on restart events.
• Rate-limit or filter GRAPH.EFFECT commands at a proxy or application layer if feasible, and review whether the command is required for your workload.

2) Patch / upgrade steps

• No fixed version is identified in the supplied intelligence. Monitor the FalkorDB project repository and advisory channels for a patched release addressing CVE-2026-88411.
• Plan an upgrade to the first vendor release that confirms the error-handling fix in /effects/effects_apply.c, and validate in a staging environment before production rollout.

3) Long-term hardening

• Adopt an inventory and exposure-management practice to detect unintended Redis/FalkorDB listeners.
• Implement continuous CVE monitoring for FalkorDB and its dependency chain.
• Apply least-privilege network segmentation so graph-database services are reachable only from intended clients.
• Establish crash-telemetry and availability monitoring to detect and correlate DoS events quickly.

References

• NVD — CVE-2026-88411: https://nvd.nist.gov/vuln/detail/CVE-2026-88411
• FalkorDB project repository and release notes (consult for patched-version status): https://github.com/FalkorDB/FalkorDB
• CWE-755 — Improper Handling of Exceptional Conditions: https://cwe.mitre.org/data/definitions/755.html
• CISA Known Exploited Vulnerabilities Catalog (CVE-2026-88411 not listed as of this report): https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• FIRST EPSS (not yet scored for CVE-2026-88411): https://www.first.org/epss

No threat actor campaigns or exploit-in-the-wild evidence are associated with CVE-2026-88411 based on the supplied intelligence.