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CVE-2026-63381— Libevent: Dangling Pointer in `evbuffer_add_buffer_reference`

CVSS 5.8 · Medium

Possible ATT&CK Techniques 1AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 2

VendorProductVersion RangeStatus
libeventlibevent>= 2.2.0-alpha, < 2.2.2-alphaaffected
< 2.1.13affected
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I. Basic Information for CVE-2026-63381

Vulnerability Information
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Vulnerability Title
Libevent: Dangling Pointer in `evbuffer_add_buffer_reference`
Source: CVE Program / CVE List V5
Vulnerability Description
Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a use-after-free in buffer.c when evbuffer_add_buffer_reference processes an output buffer whose out_total_len is zero. evbuffer_free_all_chains frees the initial empty chain without resetting outbuf->first, outbuf->last, or outbuf->last_with_datap, and APPEND_CHAIN_MULTICAST subsequently dereferences the dangling chain pointer. A caller that can drive this buffer state can cause memory corruption or a process crash. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
对未经初始化资源的使用
Source: CVE Program / CVE List V5

Affected Products

VendorProductAffected VersionsCPESubscribe
libeventlibevent >= 2.2.0-alpha, < 2.2.2-alpha -

II. Public POCs for CVE-2026-63381

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III. Intelligence Information for CVE-2026-63381

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Patches & Fixes for CVE-2026-63381 (2)

Vendor Advisories for CVE-2026-63381 (1)

Vendor Pages for CVE-2026-63381 (2)

Same Patch Batch · libevent · 2026-08-20 · 10 CVEs total

CVE-2026-633829.2 CRITICALlibevent evhttp: Multiple HTTP Parser Bugs Enable Request Smuggling
CVE-2026-633859.2 CRITICALLibevent: HTTP header handling bugs create risk of access control bypass.
CVE-2026-633848.7 HIGHLibevent: `evtag_unmarshal_header()` decodes a wire `uint32` length into a signed `int` re
CVE-2026-633838.7 HIGHLibevent: decode_tag_internal() can lead to out-of-bounds read
CVE-2026-633888.4 HIGHLibevent: Heap out-of-bounds write in bufferevent_socket_set_conn_address_ reachable via A
CVE-2026-634957.5 HIGHLibevent: Unbounded memory accumulation in WebSocket server via fragmented frames
CVE-2026-633877.0 HIGHLibevent: Off-by-one stack buffer overflow in dnsname_to_labels via crafted DNS server res
CVE-2026-633796.3 MEDIUMLibevent: HTTP Header smuggling
CVE-2026-633805.7 MEDIUMLibevent: Null Pointer Dereference in `evws_new_session`

IV. Related Vulnerabilities

Same product: libevent
Same vendor: libevent
Same weakness: CWE-908

V. Comments for CVE-2026-63381

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