EUVD-2026-67085Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Network-reachable syslog listener, no credentials required, reliable trigger, pure availability impact with no confidentiality or integrity loss.
Primary rating from Vendor (redhat).
CVSS VectorVendor: redhat
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Lifecycle Timeline
2DescriptionCVE.org
A flaw was found in rsyslog. An unauthenticated remote attacker can trigger a heap buffer overflow in the RainerScript replace() function by sending specially crafted syslog messages. This vulnerability arises from an incorrect buffer size calculation during string replacement, causing memory corruption. Successful exploitation can lead to a denial of service (DoS) for the affected system.
AnalysisAI
Heap buffer overflow in rsyslog's RainerScript replace() function allows unauthenticated remote attackers to crash affected systems by sending crafted syslog messages. The root cause is an incorrect buffer size calculation (CWE-131) during string replacement, leading to heap memory corruption and reliable denial of service. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | rsyslog must be configured to accept syslog messages from the network via a network input module (such as imudp or imtcp) bound to a network-reachable interface. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) indicates a network-exploitable, unauthenticated, zero-interaction flaw with low attack complexity - meaning the overflow trigger is expected to be highly reliable once an attacker identifies the right message payload. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker with network access to a host running rsyslog with a network input module (imudp or imtcp) enabled sends a specially crafted syslog message designed to invoke the RainerScript `replace()` function with input that triggers the undersized buffer calculation. The resulting heap overflow corrupts memory and crashes the rsyslog process, halting log collection on the target system. … |
| Remediation | Apply Red Hat-provided errata packages for the affected RHEL versions (6, 7, 8, 9, 10) as detailed in the advisory at https://access.redhat.com/security/cve/CVE-2026-78002 and tracked in Bugzilla at https://bugzilla.redhat.com/show_bug.cgi?id=2521135. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory all rsyslog instances across RHEL 6-10 environments and map external exposure on syslog port 514/UDP. …
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Same weakness CWE-131 – Incorrect Calculation of Buffer Size
View allSame technique Buffer Overflow
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External POC / Exploit Code
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