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Rocky Linux 9.6 [TuxCare] Security Update: libevent / libevent-devel / libevent-doc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1790587734)
critical Nessus Plugin ID 361498
Synopsis
The Rocky Linux host is missing one or more security updates.Description
The Rocky Linux 9.6 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1790587734 advisory.- Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent processes chunked HTTP trailers in http.c through evhttp_read_trailer and merges them into request headers. The fix introduces evhttp_parse_headers_impl_ and a temporary trailer header list. An unauthenticated remote attacker can place security-sensitive fields in trailers so that an upstream proxy and the libevent application interpret different effective headers, enabling header smuggling, authorization bypass, proxy- header spoofing, or cache poisoning. The fix parses trailers into a temporary header list and discards them instead of merging them into req->input_headers. This issue is fixed in versions 2.1.13 and 2.2.2-alpha. (CVE-2026-63379)
- 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)
- Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, the libevent evhttp parser in http.c inconsistently handles duplicate Transfer-Encoding headers, comma-separated Transfer-Encoding values, and bare line feeds in chunked framing. evhttp_find_header can select only the first header, evhttp_check_transfer_encoding_ was absent so the previous whole-string comparison fails to recognize valid lists ending in chunked, and evhttp_handle_chunked_read uses EVBUFFER_EOL_CRLF rather than EVBUFFER_EOL_CRLF_STRICT, accepting bare LF chunk terminators. When libevent is deployed behind a proxy that frames the same request differently, an unauthenticated remote attacker can desynchronize request boundaries and smuggle a second request, potentially bypassing access controls or poisoning caches. This issue is fixed in versions 2.1.13 and 2.2.2-alpha. (CVE-2026-63382)
- Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent can read beyond a contiguous evbuffer region in event_tagging.c when decode_tag_internal requests at most five bytes from evbuffer_pullup but iterates using the full logical buffer length. A fragmented evbuffer containing a six- byte malformed tag can therefore advance past the pullup window and trigger an out-of-bounds read, which can crash a process that decodes attacker-controlled tagged RPC data. This issue is fixed in versions 2.1.13 and 2.2.2-alpha. (CVE-2026-63383)
- Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has an incorrect integer conversion in event_tagging.c when evtag_unmarshal_header uses evtag_decode_int to decode an attacker-controlled uint32 payload length and returns it as a signed int. Values above INT_MAX become negative or truncated, and evtag_unmarshal_string can use the converted value in allocation sizing, producing a wrapped large allocation request and denial of service. This issue is fixed in versions 2.1.13 and 2.2.2-alpha. (CVE-2026-63384)
Note that Nessus has not tested for these issues but has instead relied only on the application's self-reported version number.
Solution
Update the affected packages based on the guidance in TuxCare advisory ALMALINUX9.6:CLSA-2026:1790587734.See Also
Plugin Details
Severity: Critical
ID: 361498
File Name: tuxcare_rocky_linux_9.6_CLSA-2026-1790587734.nasl
Version: 1.1
Type: Local
Published: 10/1/2026
Updated: 10/1/2026
Supported Sensors: Nessus Agent, Continuous Assessment, Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 4.9
Percentile: 58.35
Vendor
Vendor Severity: Important
CVSS v2
Risk Factor: High
Base Score: 9
Temporal Score: 6.7
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:C
CVSS Score Source: CVE-2026-63387
CVSS v3
Risk Factor: High
Base Score: 8.4
Temporal Score: 7.3
Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
CVSS Score Source: CVE-2026-63388
CVSS v4
Risk Factor: Critical
Base Score: 9.2
Threat Score: 7.1
Threat Vector: CVSS:4.0/E:U
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:L/SC:L/SI:L/SA:N
CVSS Score Source: CVE-2026-63385
Vulnerability Information
Required KB Items: Host/local_checks_enabled, Host/cpu, Host/RockyLinux/release, Host/RockyLinux/rpm-list, Host/OS/extended-third-party
Exploit Ease: No known exploits are available
Patch Publication Date: 9/28/2026
Vulnerability Publication Date: 8/20/2026
Reference Information
CVE: CVE-2026-63379, CVE-2026-63381, CVE-2026-63382, CVE-2026-63383, CVE-2026-63384, CVE-2026-63385, CVE-2026-63387, CVE-2026-63388
CLSA: 2026:1790587734