CVE-2026-63380 (GCVE-0-2026-63380)
Vulnerability from cvelistv5 – Published: 2026-08-20 17:52 – Updated: 2026-08-20 17:52
VLAI
EPSS
VEX
Title
Libevent: Null Pointer Dereference in `evws_new_session`
Summary
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.
Severity
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/libevent/libevent/security/adv… | x_refsource_CONFIRM |
| https://github.com/libevent/libevent/commit/825c1… | x_refsource_MISC |
| https://github.com/libevent/libevent/releases/tag… | x_refsource_MISC |
Impacted products
{
"containers": {
"cna": {
"affected": [
{
"product": "libevent",
"vendor": "libevent",
"versions": [
{
"status": "affected",
"version": "\u003c 2.2.2-alpha"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "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-\u003ews_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."
}
],
"metrics": [
{
"cvssV4_0": {
"attackComplexity": "HIGH",
"attackRequirements": "PRESENT",
"attackVector": "LOCAL",
"baseScore": 5.7,
"baseSeverity": "MEDIUM",
"privilegesRequired": "LOW",
"subAvailabilityImpact": "NONE",
"subConfidentialityImpact": "NONE",
"subIntegrityImpact": "NONE",
"userInteraction": "NONE",
"vectorString": "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",
"version": "4.0",
"vulnAvailabilityImpact": "HIGH",
"vulnConfidentialityImpact": "NONE",
"vulnIntegrityImpact": "NONE"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-416",
"description": "CWE-416: Use After Free",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-476",
"description": "CWE-476: NULL Pointer Dereference",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-20T17:52:29.458Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/libevent/libevent/security/advisories/GHSA-3rpf-frgx-xq34",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/libevent/libevent/security/advisories/GHSA-3rpf-frgx-xq34"
},
{
"name": "https://github.com/libevent/libevent/commit/825c18bd99f556b59d61200523237f264d5cc734",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/libevent/libevent/commit/825c18bd99f556b59d61200523237f264d5cc734"
},
{
"name": "https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha"
}
],
"source": {
"advisory": "GHSA-3rpf-frgx-xq34",
"discovery": "UNKNOWN"
},
"title": "Libevent: Null Pointer Dereference in `evws_new_session`"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-63380",
"datePublished": "2026-08-20T17:52:29.458Z",
"dateReserved": "2026-07-16T17:39:30.171Z",
"dateUpdated": "2026-08-20T17:52:29.458Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2026-63380\",\"sourceIdentifier\":\"security-advisories@github.com\",\"published\":\"2026-08-20T18:16:35.357\",\"lastModified\":\"2026-08-20T18:16:35.357\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"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-\u003ews_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.\"}],\"affected\":[{\"source\":\"security-advisories@github.com\",\"affectedData\":[{\"vendor\":\"libevent\",\"product\":\"libevent\",\"versions\":[{\"version\":\"\u003c 2.2.2-alpha\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV40\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"4.0\",\"vectorString\":\"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\",\"baseScore\":5.7,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"HIGH\",\"attackRequirements\":\"PRESENT\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"vulnConfidentialityImpact\":\"NONE\",\"vulnIntegrityImpact\":\"NONE\",\"vulnAvailabilityImpact\":\"HIGH\",\"subConfidentialityImpact\":\"NONE\",\"subIntegrityImpact\":\"NONE\",\"subAvailabilityImpact\":\"NONE\",\"exploitMaturity\":\"NOT_DEFINED\",\"confidentialityRequirement\":\"NOT_DEFINED\",\"integrityRequirement\":\"NOT_DEFINED\",\"availabilityRequirement\":\"NOT_DEFINED\",\"modifiedAttackVector\":\"NOT_DEFINED\",\"modifiedAttackComplexity\":\"NOT_DEFINED\",\"modifiedAttackRequirements\":\"NOT_DEFINED\",\"modifiedPrivilegesRequired\":\"NOT_DEFINED\",\"modifiedUserInteraction\":\"NOT_DEFINED\",\"modifiedVulnConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedVulnIntegrityImpact\":\"NOT_DEFINED\",\"modifiedVulnAvailabilityImpact\":\"NOT_DEFINED\",\"modifiedSubConfidentialityImpact\":\"NOT_DEFINED\",\"modifiedSubIntegrityImpact\":\"NOT_DEFINED\",\"modifiedSubAvailabilityImpact\":\"NOT_DEFINED\",\"Safety\":\"NOT_DEFINED\",\"Automatable\":\"NOT_DEFINED\",\"Recovery\":\"NOT_DEFINED\",\"valueDensity\":\"NOT_DEFINED\",\"vulnerabilityResponseEffort\":\"NOT_DEFINED\",\"providerUrgency\":\"NOT_DEFINED\"}}]},\"weaknesses\":[{\"source\":\"security-advisories@github.com\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-416\"},{\"lang\":\"en\",\"value\":\"CWE-476\"}]}],\"references\":[{\"url\":\"https://github.com/libevent/libevent/commit/825c18bd99f556b59d61200523237f264d5cc734\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha\",\"source\":\"security-advisories@github.com\"},{\"url\":\"https://github.com/libevent/libevent/security/advisories/GHSA-3rpf-frgx-xq34\",\"source\":\"security-advisories@github.com\"}]}}"
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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