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CVE-2026-63387 (GCVE-0-2026-63387)

Vulnerability from cvelistv5 – Published: 2026-08-20 17:53 – Updated: 2026-08-25 15:12
VLAI
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
7 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-25 15:11 UTC
CWE
Assigner
References
Impacted products
Vendor Product Version CPE status
libevent libevent Affected: >= 2.2.0-alpha, < 2.2.2-alpha
Affected: < 2.1.13
guessed Create a notification for this product.
Show details on NVD website
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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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