CVE-2026-92156

Executive Summary

CVE-2026-92156 is a denial-of-service vulnerability in F´ (F Prime), a framework for spaceflight and embedded software applications, affecting versions prior to 4.3.0. The flaw resides in the Svc::EventManager loqQueue_internalInterfaceHandler serialization path, where a legal Fw::LogBuffer bridged through GenericHub can exceed the remaining log-argument budget after packet descriptor, event identifier, and time-tag metadata are accounted for, triggering a serialization failure that reaches an assertion and aborts or resets the process. Deployments that bridge events into EventManager via GenericHub are affected, with impact limited to availability (CVSS 6.5, adjacent network, no privileges or user interaction required).

Technical Analysis

F´ (F Prime) is a component-based framework developed for spaceflight and embedded deployments. The Svc::EventManager component is responsible for receiving event packets, deserializing their metadata, and serializing log arguments for downstream transport. Its loqQueue_internalInterfaceHandler routine handles internally queued event traffic.

The vulnerability is classified as CWE-131: Incorrect Calculation of Buffer Size. Per the NVD description, EventManager accepts event payloads up to the framework's LogBuffer maximum size. However, an event packet serialized into a Fw::LogBuffer and forwarded into EventManager consumes part of that space with non-argument metadata: the packet descriptor, the event identifier, and the time-tag. These components reduce the budget available for the actual log arguments. When a deployment bridges events through GenericHub into EventManager and forwards a legal Fw::LogBuffer that is larger than the remaining log-argument budget, the serialization step fails and reaches an assertion. Under standard F Prime assertion handling, that assertion aborts or resets the process.

Key technical characteristics:

• The input is not malformed at the LogBuffer level — it is a "legal" buffer that is nonetheless too large once metadata overhead is subtracted. This makes the issue a boundary-calculation error rather than classic input validation failure.
• The attack surface is the event-bridging interface between GenericHub and EventManager, i.e., internally queued component traffic, not a network-facing protocol parser directly.
• The consequence is process abort/reset (denial of service), not memory corruption or code execution. CVSS subscores confirm this: C:N/I:N/A:H.
• The vulnerability requires a bridging deployment topology (GenericHub → EventManager). Standalone EventManager usage without event bridging may not expose the path described.

The gap between "maximum LogBuffer size" and "remaining log-argument budget after metadata" is the core defect; the fix in 4.3.0 presumably aligns the accepted size with the post-metadata argument budget.

Exploitation Scenarios

No public PoC is available; the attack chain below is inferred from the vulnerability class (CWE-131 size-calculation error leading to assertion-based DoS).

1. Reconnaissance/target identification: An adversary identifies an F´-based deployment that bridges events bidirectionally through GenericHub into EventManager. Such deployments expose an event-forwarding path (commonly over a ground data system link or inter-process transport). The adversary needs to be positioned to inject or relay a component-legal event payload into that bridge — consistent with the CVSS AV:A (adjacent) vector.

2. Trigger mechanism: The adversary causes an event to be emitted whose serialized Fw::LogBuffer is within the framework's global LogBuffer maximum but exceeds EventManager's remaining log-argument budget after the packet descriptor, event identifier, and time-tag are reserved. Because the buffer is legal at the LogBuffer level, ordinary size validation upstream does not reject it.

3. Execution method: The bridged payload traverses GenericHub into EventManager, reaching loqQueue_internalInterfaceHandler. Serialization of the log arguments fails against the exhausted budget, and the failure reaches an assertion.

4. Post-exploitation impact: Under standard F Prime assertion handling the process aborts or resets. For a spaceflight or embedded deployment this can mean loss of the event-handling process, a component reset, or a broader subsystem restart — a denial-of-service condition. There is no described path to data disclosure, integrity modification, or code execution.

No public exploit or Nuclei template exists; no in-the-wild exploitation has been reported. The attack requires the bridging topology and injection capability described above and is opportunistic rather than wormable.

Impact Assessment

The vulnerability is availability-only. CVSS 3.1 vector CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H yields a base score of 6.5 (Medium):

• AV:A (Adjacent): the attacker must be positioned on an adjacent network / logically adjacent bus or bridge path, not remote over the internet.
• AC:L (Low): no special conditions beyond the bridging topology are described.
• PR:N / UI:N: no authentication or user interaction required.
• S:U: impact is scoped to the vulnerable component/process.
• C:N / I:N: no confidentiality or integrity impact.
• A:H (High): total loss of availability of the affected process.

Blast radius: F´ deployments that (a) run versions prior to 4.3.0, and (b) bridge events through GenericHub into EventManager. Spaceflight missions, satellite ground segments, robotics, and other embedded systems built on F Prime fall into this class. A process abort or reset in such environments may disrupt telemetry event handling and, in tightly coupled systems, cascade into larger resets. Because the trigger is a "legal" payload, operational monitoring may treat the traffic as normal until the assertion fires. No affected commercial product name is provided by the vendor data; scope must be assessed per deployment based on whether event bridging is used.

Detection Guidance

Sigma Rule

title: F Prime EventManager Assertion DoS via GenericHub Event Bridging id: 8a41c2f7-3b9d-4e21-9c77-0f2e5b6a1d08 status: experimental description: Detects process abort/reset patterns consistent with CVE-2026-92156, where a bridged legal Fw::LogBuffer exceeds EventManager remaining log-argument budget and reaches an assertion in loqQueue_internalInterfaceHandler. references:

• https://nvd.nist.gov/vuln/detail/CVE-2026-92156 author: valtersit.com date: 2026-01-01 logsource: category: application product: fprime detection: keywords_assert:
  • 'loqQueue_internalInterfaceHandler'
  • 'EventManager'
  • 'Assertion' keywords_fail:
  • 'serialization failure'
  • 'log-argument budget'
  • 'LogBuffer' condition: keywords_assert and keywords_fail falsepositives:
• Development builds with verbose assertion logging level: medium

YARA Rule

rule FPrime_EventManager_Assertion_Boundary_CVE_2026_92156
{
    meta:
        description = "Detects embedded F Prime build artifacts referencing the vulnerable EventManager serialization path (CVE-2026-92156)"
        author = "valtersit.com"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2026-92156"
        date = "2026-01-01"
        severity = "medium"

    strings:
        $s1 = "loqQueue_internalInterfaceHandler" ascii wide
        $s2 = "EventManager" ascii wide
        $s3 = "GenericHub" ascii wide
        $s4 = "LogBuffer" ascii wide
        $s5 = "RemainingLogArgumentBudget" ascii wide

    condition:
        (uint16(0) == 0x457F or uint32(0) == 0x464C457F) and
        filesize < 50MB and
        $s2 and $s4 and ($s1 or $s3)
}

Suricata IDS Rule

alert tcp any any -> any any (msg:"CVE-2026-92156 F Prime EventManager LogBuffer Assertion DoS Attempt"; flow:to_server,established; content:"|46 77 3A 3A|LogBuffer"; content:"EventManager"; distance:0; threshold:type both, track by_src, count 20, seconds 10; classtype:attempted-dos; reference:cve,2026-92156; reference:url,nvd.nist.gov/vuln/detail/CVE-2026-92156; sid:202692156; rev:1;)

Elastic Detection

process where event.type == "end" and process.name : ("fprime", "FPrime", "Gds", "generic_hub", "EventManager") and (process.exit_code != 0 or process.exit_code == 134 or process.exit_code == 139) and wildcard(process.command_line, "EventManager") and wildcard(process.command_line, "GenericHub")

Splunk SPL Query

index=fprime_logs (sourcetype=fprime:console OR sourcetype=fprime:eventmanager) | search ("loqQueue_internalInterfaceHandler" OR "EventManager") ("Assertion" OR "assertion failed" OR "serialization failure" OR "LogBuffer") | stats count AS failures, values(host) AS hosts, min(_time) AS first_seen, max(_time) AS last_seen by process_name, host | where failures >= 1 | convert ctime(first_seen) ctime(last_seen)

Wazuh OSSEC Rule

json loqQueue_internalInterfaceHandler EventManager CVE-2026-92156: F Prime EventManager assertion triggered by bridged LogBuffer exceeding log-argument budget (potential DoS). T1499 dos, EventManager serialization failure F Prime EventManager serialization failure observed - correlation may indicate CVE-2026-92156. dos,fprime,

Mitigation & Patch Guidance

Patch confidence: 0/4 — UNPATCHED. No patch evidence from any tracked source, no vendor advisory, no OSV package data, and no PoC/exploit records. The NVD description states the issue is fixed in version 4.3.0, but this is not corroborated by any tracked patch artifact.

1. Immediate mitigations:

• Inventory all F´ deployments running versions prior to 4.3.0 and identify those that bridge events through GenericHub into EventManager. These are the only deployments exposed by the described mechanism.
• Reduce the maximum event argument size permitted to be emitted across the bridge, so that serialized Fw::LogBuffer payloads stay within the post-metadata log-argument budget of EventManager. This directly mitigates CWE-131 in this path.
• Where feasible, avoid untrusted bridging of event traffic and restrict who can inject payloads into the GenericHub-to-EventManager path, reducing the AV:A exposure.
• Confirm assertion-handling configuration: under standard F Prime assertions the process aborts or resets. If a deployment can tolerate a graceful rejection instead of abort while a fix is pending, adjust handling carefully — but treat this as a temporary measure only.

2. Patch/upgrade steps:

• Upgrade to F´ (F Prime) 4.3.0 or later, which per the NVD description resolves the issue.
• Because no formal vendor fix evidence is tracked (Patch Confidence 0/4), independently verify the fix in release notes and validate with a regression test that emits a maximal legal Fw::LogBuffer through the GenericHub bridge into EventManager and confirms no assertion occurs.
• Re-check all submodules and dependents pinned to pre-4.3.0 F Prime versions; embedded builds frequently vendor the framework.

3. Long-term hardening:

• Add unit/integration tests that exercise boundary conditions at the intersection of LogBuffer maximum size and metadata overhead, based on CWE-131 (buffer-size miscalculation).
• Instrument event handling so assertion-driven exits are alarmed and correlated, enabling fast detection of availability incidents.
• Adopt a dependency-pinning and SBOM process so affected F Prime versions and bridging topologies are discoverable across fleets.

References

• NVD — CVE-2026-92156: https://nvd.nist.gov/vuln/detail/CVE-2026-92156
• MITRE CWE-131 — Incorrect Calculation of Buffer Size: https://cwe.mitre.org/data/definitions/131.html
• F´ (F Prime) project repository and release notes for 4.3.0: https://github.com/nasa/fprime (verify 4.3.0 release contents directly)
• ATT&CK T1499 — Endpoint Denial of Service: https://attack.mitre.org/techniques/T1499/
• CISA KEV catalog: Not listed — CVE-2026-92156 is not in CISA KEV, and no in-the-wild exploitation or threat actor campaign has been reported as of this report.

◈ SOURCE Analysis & enrichment: valtersit.com/cve/CVE-2026-92156/ · CVE data: NVD/MITRE (public domain) · © 2026 ValtersIT Hub