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libevent CVE-2026-63380

| EUVDEUVD-2026-63506 MEDIUM
Use After Free (CWE-416)
2026-08-20 GitHub_M
Use After Free Denial Of Service Memory Corruption Libevent
5.7
CVSS 4.0 · Vendor: GitHub_M
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Severity by source

Vendor (GitHub_M) PRIMARY
5.7 MEDIUM
CVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
4.7 MEDIUM

Local access and low privileges required to reach the WebSocket error path; scope unchanged as only the vulnerable process crashes; no confidentiality or integrity impact.

3.1 AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H
4.0 AV:L/AC:H/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
SUSE
4.7 MEDIUM
AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

Primary rating from Vendor (GitHub_M).

CVSS VectorVendor: GitHub_M

Attack Vector
Local
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

4
Source Code Evidence Fetched
Aug 20, 2026 - 18:39 vuln.today
Analysis Generated
Aug 20, 2026 - 18:39 vuln.today
Patch available
Aug 20, 2026 - 18:03 EUVD
CVE Published
Aug 20, 2026 - 17:52 cve.org
MEDIUM 5.7

DescriptionCVE.org

Libevent is an event notification library. Prior to 2.2.2-alpha, libevent can dereference invalid list pointers in ws.c when evws_new_session enters its error path after evhttp_start_ws_ succeeds but bufferevent_enable_locking_ fails. evws_connection_free sees a non-null http_server and unconditionally calls TAILQ_REMOVE even though the session was never inserted into http_server->ws_sessions. A local caller able to induce this allocation or locking failure can crash the process. This issue is fixed in version 2.2.2-alpha.

AnalysisAI

Use-after-free in libevent's WebSocket session initialization (ws.c) before version 2.2.2-alpha allows a local low-privileged caller to crash the hosting process by inducing a locking failure. When evhttp_start_ws_ succeeds but bufferevent_enable_locking_ subsequently fails, the cleanup function evws_connection_free calls TAILQ_REMOVE on a list the session was never inserted into, dereferencing an invalid pointer. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

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Vulnerability AssessmentAI

Exploitation The attacker must have local, low-privilege access to the target system (AV:L, PR:L per CVSS 4.0 vector). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 4.0 vector (AV:L/AC:H/AT:P/PR:L/UI:N/VA:H) accurately reflects a constrained local denial-of-service with no code execution potential. … 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 Upgrade to libevent 2.2.2-alpha, available at https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha, which contains the fix in commit 825c18bd99f556b59d61200523237f264d5cc734. … Detailed patch versions, workarounds, and compensating controls in full report.
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Same weakness CWE-416 – Use After Free

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Same technique Use After Free

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Vendor StatusVendor

SUSE

Severity: Moderate
Product Status
SUSE Linux Enterprise Desktop 15 SP7 Affected
SUSE Linux Enterprise High Performance Computing 12 Affected
SUSE Linux Enterprise High Performance Computing 15 SP7 Affected
SUSE Linux Enterprise Micro 5.3 Affected
SUSE Linux Enterprise Micro 5.4 Affected

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CVE-2026-63380 vulnerability details – vuln.today
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