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BDU:2026-12663 (CVE-2026-63387)
Vulnerability from fstec – Published: 2026-08-26 – Updated: 2026-08-26 – View on bdu.fstec.ru Exploit publicly available Fixed
VLAI
Title
Уязвимость функции dnsname_to_labels() библиотеки асинхронного уведомления событий Libevent, позволяющая нарушителю вызвать отказ в обслуживании
Summary
Уязвимость функции dnsname_to_labels() библиотеки асинхронного уведомления событий Libevent связана с выходом операции за границы буфера в памяти. Эксплуатация уязвимости может позволить нарушителю, действующему удаленно, вызвать отказ в обслуживании
Severity
Class
Code vulnerability
Status
Confirmed by the vendor
Exploitation
Data structure manipulation
Incidents
Being clarified
Remediation
Software update
CWE
Aliases
References
Impacted products
1 product
from 1 vendor
Vendors
Libevent project
Products
Libevent
Versions
до 2.1.12 включительно (Libevent), до 2.2.1-alpha включительно (Libevent)
Product types
Application software
Mitigations
{
"CVSS 2.0": "AV:N/AC:H/Au:N/C:P/I:P/A:C",
"CVSS 3.0": "AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H",
"CVSS 4.0": null,
"remediation_\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": null,
"remediation_\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435": null,
"\u0412\u0435\u043d\u0434\u043e\u0440 \u041f\u041e": "Libevent project",
"\u0412\u0435\u0440\u0441\u0438\u044f \u041f\u041e": "\u0434\u043e 2.1.12 \u0432\u043a\u043b\u044e\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e (Libevent), \u0434\u043e 2.2.1-alpha \u0432\u043a\u043b\u044e\u0447\u0438\u0442\u0435\u043b\u044c\u043d\u043e (Libevent)",
"\u0412\u043e\u0437\u043c\u043e\u0436\u043d\u044b\u0435 \u043c\u0435\u0440\u044b \u043f\u043e \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044e": "\u0418\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 \u0440\u0435\u043a\u043e\u043c\u0435\u043d\u0434\u0430\u0446\u0438\u0439 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u044f:\nhttps://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47\nhttps://github.com/libevent/libevent/releases/tag/release-2.1.13-stable\nhttps://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha",
"\u0414\u0430\u0442\u0430 \u0432\u044b\u044f\u0432\u043b\u0435\u043d\u0438\u044f": "01.07.2026",
"\u0414\u0430\u0442\u0430 \u043f\u043e\u0441\u043b\u0435\u0434\u043d\u0435\u0433\u043e \u043e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u044f": "26.08.2026",
"\u0414\u0430\u0442\u0430 \u043f\u0443\u0431\u043b\u0438\u043a\u0430\u0446\u0438\u0438": "26.08.2026",
"\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440": "BDU:2026-12663",
"\u0418\u0434\u0435\u043d\u0442\u0438\u0444\u0438\u043a\u0430\u0442\u043e\u0440\u044b \u0434\u0440\u0443\u0433\u0438\u0445 \u0441\u0438\u0441\u0442\u0435\u043c \u043e\u043f\u0438\u0441\u0430\u043d\u0438\u0439 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "CVE-2026-63387, GHSA-58rx-7448-jw47",
"\u0418\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f \u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0430",
"\u041a\u043b\u0430\u0441\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u043a\u043e\u0434\u0430",
"\u041d\u0430\u0437\u0432\u0430\u043d\u0438\u0435 \u041f\u041e": "Libevent",
"\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u041e\u0421 \u0438 \u0442\u0438\u043f \u0430\u043f\u043f\u0430\u0440\u0430\u0442\u043d\u043e\u0439 \u043f\u043b\u0430\u0442\u0444\u043e\u0440\u043c\u044b": null,
"\u041d\u0430\u0438\u043c\u0435\u043d\u043e\u0432\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0444\u0443\u043d\u043a\u0446\u0438\u0438 dnsname_to_labels() \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0438 \u0430\u0441\u0438\u043d\u0445\u0440\u043e\u043d\u043d\u043e\u0433\u043e \u0443\u0432\u0435\u0434\u043e\u043c\u043b\u0435\u043d\u0438\u044f \u0441\u043e\u0431\u044b\u0442\u0438\u0439 Libevent, \u043f\u043e\u0437\u0432\u043e\u043b\u044f\u044e\u0449\u0430\u044f \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e \u0432\u044b\u0437\u0432\u0430\u0442\u044c \u043e\u0442\u043a\u0430\u0437 \u0432 \u043e\u0431\u0441\u043b\u0443\u0436\u0438\u0432\u0430\u043d\u0438\u0438",
"\u041d\u0430\u043b\u0438\u0447\u0438\u0435 \u044d\u043a\u0441\u043f\u043b\u043e\u0439\u0442\u0430": "\u0421\u0443\u0449\u0435\u0441\u0442\u0432\u0443\u0435\u0442 \u0432 \u043e\u0442\u043a\u0440\u044b\u0442\u043e\u043c \u0434\u043e\u0441\u0442\u0443\u043f\u0435",
"\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "\u041f\u0435\u0440\u0435\u043f\u043e\u043b\u043d\u0435\u043d\u0438\u0435 \u0431\u0443\u0444\u0435\u0440\u0430 \u0432 \u0441\u0442\u0435\u043a\u0435 (CWE-121), \u041e\u0448\u0438\u0431\u043a\u0430 \u0435\u0434\u0438\u043d\u0438\u0447\u043d\u043e\u0433\u043e \u0441\u043c\u0435\u0449\u0435\u043d\u0438\u044f (CWE-193), \u0417\u0430\u043f\u0438\u0441\u044c \u0437\u0430 \u0433\u0440\u0430\u043d\u0438\u0446\u0430\u043c\u0438 \u0431\u0443\u0444\u0435\u0440\u0430 (CWE-787)",
"\u041e\u043f\u0438\u0441\u0430\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c \u0444\u0443\u043d\u043a\u0446\u0438\u0438 dnsname_to_labels() \u0431\u0438\u0431\u043b\u0438\u043e\u0442\u0435\u043a\u0438 \u0430\u0441\u0438\u043d\u0445\u0440\u043e\u043d\u043d\u043e\u0433\u043e \u0443\u0432\u0435\u0434\u043e\u043c\u043b\u0435\u043d\u0438\u044f \u0441\u043e\u0431\u044b\u0442\u0438\u0439 Libevent \u0441\u0432\u044f\u0437\u0430\u043d\u0430 \u0441 \u0432\u044b\u0445\u043e\u0434\u043e\u043c \u043e\u043f\u0435\u0440\u0430\u0446\u0438\u0438 \u0437\u0430 \u0433\u0440\u0430\u043d\u0438\u0446\u044b \u0431\u0443\u0444\u0435\u0440\u0430 \u0432 \u043f\u0430\u043c\u044f\u0442\u0438. \u042d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u044f \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438 \u043c\u043e\u0436\u0435\u0442 \u043f\u043e\u0437\u0432\u043e\u043b\u0438\u0442\u044c \u043d\u0430\u0440\u0443\u0448\u0438\u0442\u0435\u043b\u044e, \u0434\u0435\u0439\u0441\u0442\u0432\u0443\u044e\u0449\u0435\u043c\u0443 \u0443\u0434\u0430\u043b\u0435\u043d\u043d\u043e, \u0432\u044b\u0437\u0432\u0430\u0442\u044c \u043e\u0442\u043a\u0430\u0437 \u0432 \u043e\u0431\u0441\u043b\u0443\u0436\u0438\u0432\u0430\u043d\u0438\u0438",
"\u041f\u043e\u0441\u043b\u0435\u0434\u0441\u0442\u0432\u0438\u044f \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": null,
"\u041f\u0440\u043e\u0447\u0430\u044f \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u044f": null,
"\u0421\u0432\u044f\u0437\u044c \u0441 \u0438\u043d\u0446\u0438\u0434\u0435\u043d\u0442\u0430\u043c\u0438 \u0418\u0411": "\u0414\u0430\u043d\u043d\u044b\u0435 \u0443\u0442\u043e\u0447\u043d\u044f\u044e\u0442\u0441\u044f",
"\u0421\u043e\u0441\u0442\u043e\u044f\u043d\u0438\u0435 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041e\u043f\u0443\u0431\u043b\u0438\u043a\u043e\u0432\u0430\u043d\u0430",
"\u0421\u043f\u043e\u0441\u043e\u0431 \u0443\u0441\u0442\u0440\u0430\u043d\u0435\u043d\u0438\u044f": "\u041e\u0431\u043d\u043e\u0432\u043b\u0435\u043d\u0438\u0435 \u043f\u0440\u043e\u0433\u0440\u0430\u043c\u043c\u043d\u043e\u0433\u043e \u043e\u0431\u0435\u0441\u043f\u0435\u0447\u0435\u043d\u0438\u044f",
"\u0421\u043f\u043e\u0441\u043e\u0431 \u044d\u043a\u0441\u043f\u043b\u0443\u0430\u0442\u0430\u0446\u0438\u0438": "\u041c\u0430\u043d\u0438\u043f\u0443\u043b\u0438\u0440\u043e\u0432\u0430\u043d\u0438\u0435 \u0441\u0442\u0440\u0443\u043a\u0442\u0443\u0440\u0430\u043c\u0438 \u0434\u0430\u043d\u043d\u044b\u0445",
"\u0421\u0441\u044b\u043b\u043a\u0438 \u043d\u0430 \u0438\u0441\u0442\u043e\u0447\u043d\u0438\u043a\u0438": "https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47\nhttps://github.com/libevent/libevent/releases/tag/release-2.1.13-stable\nhttps://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha",
"\u0421\u0442\u0430\u0442\u0443\u0441 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u041f\u043e\u0434\u0442\u0432\u0435\u0440\u0436\u0434\u0435\u043d\u0430 \u043f\u0440\u043e\u0438\u0437\u0432\u043e\u0434\u0438\u0442\u0435\u043b\u0435\u043c",
"\u0422\u0438\u043f \u041f\u041e": "\u041f\u0440\u0438\u043a\u043b\u0430\u0434\u043d\u043e\u0435 \u041f\u041e \u0438\u043d\u0444\u043e\u0440\u043c\u0430\u0446\u0438\u043e\u043d\u043d\u044b\u0445 \u0441\u0438\u0441\u0442\u0435\u043c",
"\u0422\u0438\u043f \u043e\u0448\u0438\u0431\u043a\u0438 CWE": "CWE-121, CWE-193, CWE-787",
"\u0423\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 \u0443\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u0438": "\u0421\u0440\u0435\u0434\u043d\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 2.0 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 6,6)\n\u0412\u044b\u0441\u043e\u043a\u0438\u0439 \u0443\u0440\u043e\u0432\u0435\u043d\u044c \u043e\u043f\u0430\u0441\u043d\u043e\u0441\u0442\u0438 (\u0431\u0430\u0437\u043e\u0432\u0430\u044f \u043e\u0446\u0435\u043d\u043a\u0430 CVSS 3.1 \u0441\u043e\u0441\u0442\u0430\u0432\u043b\u044f\u0435\u0442 7)"
}
CVE-2026-63387 (GCVE-0-2026-63387)
Vulnerability from cvelistv5 – Published: 2026-08-20 17:53 – Updated: 2026-08-25 15:12
VLAI
EPSS
VEX
Title
Libevent: Off-by-one stack buffer overflow in dnsname_to_labels via crafted DNS server response
Summary
Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an off-by-one stack buffer overflow in evdns.c when dnsname_to_labels formats a name-bearing DNS record at the end of the 64 KB stack buffer allocated by evdns_server_request_format_response. The final-label check permits j plus label_len plus one to equal buf_len, after which the terminating null byte is written to buf[buf_len]. A crafted DNS server response containing PTR, CNAME, MX, NS, or SOA data can trigger the one-byte out-of-bounds write and crash or corrupt the process. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.
Severity
SSVC
Exploitation: poc
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-25 15:11 UTC
Assigner
References
3 references
| URL | Tags |
|---|---|
| https://github.com/libevent/libevent/security/adv… | x_refsource_CONFIRM |
| https://github.com/libevent/libevent/releases/tag… | x_refsource_MISC |
| https://github.com/libevent/libevent/releases/tag… | x_refsource_MISC |
Impacted products
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-63387",
"options": [
{
"Exploitation": "poc"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-08-25T15:11:49.042805Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-08-25T15:12:12.129Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"references": [
{
"tags": [
"exploit"
],
"url": "https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47"
}
],
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"product": "libevent",
"vendor": "libevent",
"versions": [
{
"status": "affected",
"version": "\u003e= 2.2.0-alpha, \u003c 2.2.2-alpha"
},
{
"status": "affected",
"version": "\u003c 2.1.13"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an off-by-one stack buffer overflow in evdns.c when dnsname_to_labels formats a name-bearing DNS record at the end of the 64 KB stack buffer allocated by evdns_server_request_format_response. The final-label check permits j plus label_len plus one to equal buf_len, after which the terminating null byte is written to buf[buf_len]. A crafted DNS server response containing PTR, CNAME, MX, NS, or SOA data can trigger the one-byte out-of-bounds write and crash or corrupt the process. This issue is fixed in versions 2.1.13 and 2.2.2-alpha."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "HIGH",
"attackVector": "NETWORK",
"availabilityImpact": "HIGH",
"baseScore": 7,
"baseSeverity": "HIGH",
"confidentialityImpact": "LOW",
"integrityImpact": "LOW",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H",
"version": "3.1"
}
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-121",
"description": "CWE-121: Stack-based Buffer Overflow",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-193",
"description": "CWE-193: Off-by-one Error",
"lang": "en",
"type": "CWE"
}
]
},
{
"descriptions": [
{
"cweId": "CWE-787",
"description": "CWE-787: Out-of-bounds Write",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-08-20T17:53:41.863Z",
"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"shortName": "GitHub_M"
},
"references": [
{
"name": "https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47",
"tags": [
"x_refsource_CONFIRM"
],
"url": "https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47"
},
{
"name": "https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable",
"tags": [
"x_refsource_MISC"
],
"url": "https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable"
},
{
"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-58rx-7448-jw47",
"discovery": "UNKNOWN"
},
"title": "Libevent: Off-by-one stack buffer overflow in dnsname_to_labels via crafted DNS server response"
}
},
"cveMetadata": {
"assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
"assignerShortName": "GitHub_M",
"cveId": "CVE-2026-63387",
"datePublished": "2026-08-20T17:53:41.863Z",
"dateReserved": "2026-07-16T17:39:30.171Z",
"dateUpdated": "2026-08-25T15:12:12.129Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}