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.

The remote Fedora 45 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-0a83f1b852 advisory.

    # Update to 2.1.13.

    The following security vulnerabilites are fixed in this update:

    - GHSA-fj29-64w6-73h6 CVE-2026-63383 <https://github.com/libevent/libevent/security/advisories/GHSA-     fj29-64w6-73h6>
    - GHSA-45c6-qx49-89m8 CVE-2026-63384     <https://github.com/libevent/libevent/security/advisories/GHSA-45c6-qx49-89m8>
    - GHSA-cvq5-vrvr-j338 CVE-2026-63388 <https://github.com/libevent/libevent/security/advisories/GHSA-     cvq5-vrvr-j338>
    - GHSA-58rx-7448-jw47 CVE-2026-63387     <https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47>
    - GHSA-2gmv-p5m7-98p6 CVE-2026-63379     <https://github.com/libevent/libevent/security/advisories/GHSA-2gmv-p5m7-98p6>
    - GHSA-c2pj-cg4r-88c8 CVE-2026-63381 <https://github.com/libevent/libevent/security/advisories/GHSA-c2pj-     cg4r-88c8>
    - GHSA-q39v-w2g7-gr8j CVE-2026-63382     <https://github.com/libevent/libevent/security/advisories/GHSA-q39v-w2g7-gr8j>
    - GHSA-jcwh-pvf2-73p2 CVE-2026-63385 <https://github.com/libevent/libevent/security/advisories/GHSA-jcwh-     pvf2-73p2>


Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Debian 13 host has packages installed that are affected by multiple vulnerabilities as referenced in the dsa-6493 advisory.

    - -------------------------------------------------------------------------     Debian Security Advisory DSA-6493-1                   security@debian.org     https://www.debian.org/security/                                  Aron Xu     September 11, 2026                    https://www.debian.org/security/faq
    - -------------------------------------------------------------------------

    Package        : libevent     CVE ID         : CVE-2026-63379 CVE-2026-63381 CVE-2026-63382 CVE-2026-63383                      CVE-2026-63384 CVE-2026-63385 CVE-2026-63387 CVE-2026-63388

    Several vulnerabilities were discovered in libevent, an asynchronous event     notification library.

    The HTTP implementation (evhttp) handled Transfer-Encoding and     Content-Length headers, chunked-encoding line terminators, header line     folding and chunked trailers too permissively, which could allow HTTP     request smuggling, header injection or access control bypass when a     libevent-based server or client is combined with an HTTP proxy.

    Out-of-bounds memory accesses in the DNS (evdns), tagged RPC     (evtag/evrpc) and buffered socket (bufferevent) code, and a     use-after-free in evbuffer, could result in denial of service or     potentially the execution of arbitrary code when processing untrusted     input.

    For the stable distribution (trixie), these problems have been fixed in     version 2.1.13-stable-1~deb13u1.

    We recommend that you upgrade your libevent packages.

    For the detailed security status of libevent please refer to     its security tracker page at:
    https://security-tracker.debian.org/tracker/libevent

    Further information about Debian Security Advisories, how to apply     these updates to your system and frequently asked questions can be     found at: https://www.debian.org/security/

    Mailing list: debian-security-announce@lists.debian.org

Tenable has extracted the preceding description block directly from the Debian security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 43 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-728dd9f704 advisory.

    # Update to 2.1.13.

    The following security vulnerabilites are fixed in this update:

    - GHSA-fj29-64w6-73h6 CVE-2026-63383 <https://github.com/libevent/libevent/security/advisories/GHSA-     fj29-64w6-73h6>
    - GHSA-45c6-qx49-89m8 CVE-2026-63384     <https://github.com/libevent/libevent/security/advisories/GHSA-45c6-qx49-89m8>
    - GHSA-cvq5-vrvr-j338 CVE-2026-63388 <https://github.com/libevent/libevent/security/advisories/GHSA-     cvq5-vrvr-j338>
    - GHSA-58rx-7448-jw47 CVE-2026-63387     <https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47>
    - GHSA-2gmv-p5m7-98p6 CVE-2026-63379     <https://github.com/libevent/libevent/security/advisories/GHSA-2gmv-p5m7-98p6>
    - GHSA-c2pj-cg4r-88c8 CVE-2026-63381 <https://github.com/libevent/libevent/security/advisories/GHSA-c2pj-     cg4r-88c8>
    - GHSA-q39v-w2g7-gr8j CVE-2026-63382     <https://github.com/libevent/libevent/security/advisories/GHSA-q39v-w2g7-gr8j>
    - GHSA-jcwh-pvf2-73p2 CVE-2026-63385 <https://github.com/libevent/libevent/security/advisories/GHSA-jcwh-     pvf2-73p2>

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The remote Fedora 44 host has a package installed that is affected by multiple vulnerabilities as referenced in the FEDORA-2026-72d10c874d advisory.

    # Update to 2.1.13.

    The following security vulnerabilites are fixed in this update:

    - GHSA-fj29-64w6-73h6 CVE-2026-63383 <https://github.com/libevent/libevent/security/advisories/GHSA-     fj29-64w6-73h6>
    - GHSA-45c6-qx49-89m8 CVE-2026-63384     <https://github.com/libevent/libevent/security/advisories/GHSA-45c6-qx49-89m8>
    - GHSA-cvq5-vrvr-j338 CVE-2026-63388 <https://github.com/libevent/libevent/security/advisories/GHSA-     cvq5-vrvr-j338>
    - GHSA-58rx-7448-jw47 CVE-2026-63387     <https://github.com/libevent/libevent/security/advisories/GHSA-58rx-7448-jw47>
    - GHSA-2gmv-p5m7-98p6 CVE-2026-63379     <https://github.com/libevent/libevent/security/advisories/GHSA-2gmv-p5m7-98p6>
    - GHSA-c2pj-cg4r-88c8 CVE-2026-63381 <https://github.com/libevent/libevent/security/advisories/GHSA-c2pj-     cg4r-88c8>
    - GHSA-q39v-w2g7-gr8j CVE-2026-63382     <https://github.com/libevent/libevent/security/advisories/GHSA-q39v-w2g7-gr8j>
    - GHSA-jcwh-pvf2-73p2 CVE-2026-63385 <https://github.com/libevent/libevent/security/advisories/GHSA-jcwh-     pvf2-73p2>

Tenable has extracted the preceding description block directly from the Fedora security advisory.

Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.

The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2026-106192 advisory.

    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.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - 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. (CVE-2026-63381)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
344983	Fedora 45 : libevent (2026-0a83f1b852)	Nessus	Fedora Local Security Checks	Local	critical
344780	Debian dsa-6493 : libevent-2.1-7t64 - security update	Nessus	Debian Local Security Checks	Local	critical
344676	Fedora 43 : libevent (2026-728dd9f704)	Nessus	Fedora Local Security Checks	Local	critical
343966	Fedora 44 : libevent (2026-72d10c874d)	Nessus	Fedora Local Security Checks	Local	critical
342870	Unity Linux 20.1050e / 20.1060e / 20.1070e Security Update: libevent (UTSA-2026-106192)	Nessus	Unity Linux Local Security Checks	Local	medium
338655	Linux Distros Unpatched Vulnerability : CVE-2026-63381	Nessus	Misc.	Local	medium

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