> CVE-2026-63387 [HIGH]

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PUBLISHED
2026-08-20 18:16
MODIFIED
2026-08-20 18:16
CVSS_SCORE V3
7.0
EPSS (Prob. Exploit)
0.42%
Top 65.6%
DATA SOURCES:
NVD đź”— 2026-08-20 CWE MITRE đź”— 2026-09-01 FIRST EPSS đź”— 2026-10-18 OSV đź”— 2026-10-26 MSRC đź”— 2026-09-01

> DESCRIPTION

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.

> AFFECTED_PRODUCTS

ℹ️ Aucun produit affecté n'a encore été publié par NVD pour cette CVE.

> CVSS V3 METRICS

CVSS_VECTOR
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
EXPLOITABILITY
2.2
IMPACT
4.7

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Network (N)
Exploit possible à distance via réseau (HTTP, API, etc.)
AC (Complexité d'Attaque)
Attack Complexity
High (H)
Conditions spécifiques doivent être réunies pour exploiter
PR (Privilèges Requis)
Privileges Required
None (N)
Aucune authentification requise
UI (Interaction Utilisateur)
User Interaction
None (N)
Aucune interaction utilisateur nécessaire
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
Low (L)
Divulgation limitée d'informations
I (Impact Intégrité)
Integrity Impact
Low (L)
Modification limitée des données possible
A (Impact Disponibilité)
Availability Impact
High (H)
Interruption totale du service possible

> RÉSUMÉ DES IMPACTS

Confidentialité
Low
Divulgation limitée d'informations
Intégrité
Low
Modification limitée des données possible
Disponibilité
High
Interruption totale du service possible

> WEAKNESSES

CWE-121 CWE-193 CWE-787

> CWE DETAILED DESCRIPTIONS

CWE-121: Stack-based Buffer Overflow - A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function). | CWE-193: Off-by-one Error - A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value. | CWE-787: Out-of-bounds Write - The product writes data past the end, or before the beginning, of the intended buffer.

> RED HAT SECURITY ADVISORIES

Red Hat Security Advisory: Red Hat Hardened Images RPMs Security Update
An update for Red Hat Hardened Images RPMs is now available.
Red Hat Security Advisory: libevent security update
An update for libevent is now available for Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System...
Red Hat Security Advisory: libevent security update
An update for libevent is now available for Red Hat Enterprise Linux 10. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System...
Red Hat Security Advisory: libevent security update
An update for libevent is now available for Red Hat Enterprise Linux 8. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System...
Red Hat Security Advisory: Red Hat Update Infrastructure 5.3 security update
The latest release of Red Hat Update Infrastructure. For more details, see the product documentation.
Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.20.1
cert-manager Operator for Red Hat OpenShift 1.20.1
Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.20.1
cert-manager Operator for Red Hat OpenShift 1.20.1
Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.20.1
cert-manager Operator for Red Hat OpenShift 1.20.1
Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.20.1
cert-manager Operator for Red Hat OpenShift 1.20.1
Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.20.1
cert-manager Operator for Red Hat OpenShift 1.20.1
Red Hat Security Advisory: cert-manager Operator for Red Hat OpenShift 1.20.1
cert-manager Operator for Red Hat OpenShift 1.20.1

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

Libevent: Off-by-one stack buffer overflow in dnsname_to_labels via crafted DNS server response

AFFECTED PACKAGES:
Unknown / Unknown
23 versions affected
ALIASES:
GHSA-58rx-7448-jw47

> HISTORIQUE DES MODIFICATIONS

Première apparition
20/08/2026 18:16
Source: NVD
đź“Š ENRICHISSEMENT 01/09/2026 06:02
CWE
Champ modifié: Description CWE
Ancienne valeur:
N/A
Nouvelle valeur:
CWE-121: Stack-based Buffer Overflow - A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a para...
Total des modifications: 1 Dernière mise à jour: 1 month ago

> REFERENCES

https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable
https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha
https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47
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