EUVD-2026-70978
GHSA-vj89-2c25-485x
Severity by source
AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Confirmed impact is daemon crash (DoS); RCE is speculative, so C and I are N; AV:A and AC:H accurately reflect multicast adjacency and heap-exploitation complexity.
Primary rating from Vendor (redhat).
CVSS VectorVendor: redhat
Lifecycle Timeline
2DescriptionCVE.org
A heap-based buffer overflow was found in Corosync's Totem Process Group (totempg) message reassembly. When processing fragmented multicast messages, the buffer used to reassemble fragments lacks a runtime bounds check in release builds. A network-adjacent attacker able to send crafted multicast protocol messages to the cluster could cause a heap buffer overflow with attacker-controlled data. This can crash the Corosync daemon, causing a denial of service to the entire cluster, and may potentially allow further exploitation given sufficient heap-corruption control.
AnalysisAI
Heap buffer overflow in Corosync's Totem Process Group (totempg) message reassembly exposes high-availability clusters to network-adjacent unauthenticated attack. When processing fragmented multicast messages, the reassembly buffer lacks runtime bounds checking in release builds, allowing an attacker on the same cluster network to trigger heap corruption with attacker-controlled data. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The attacker must be network-adjacent - specifically able to send IP multicast packets to the Corosync cluster's heartbeat multicast group (default 226.94.1.1, UDP port 5405) and receive responses. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The provided CVSS vector (AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H, score 7.5) correctly reflects network-adjacent access and high complexity, but the C:H and I:H metrics appear aspirational - the description's language ('may potentially allow further exploitation') indicates DoS is the confirmed outcome and RCE is speculative. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Apply the Red Hat-issued errata for Corosync when published for the applicable RHEL or OpenShift release stream; monitor https://access.redhat.com/security/cve/CVE-2026-81665 for patch availability. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all production Corosync deployments and restrict cluster network connectivity to only known, authorized nodes through firewall or network segmentation. …
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External POC / Exploit Code
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