AlmaLinux 9.6 [TuxCare] Security Update: compat-libpthread-nonshared / glibc / glibc-all-langpacks / etc Multiple Vulnerabilities (ALMALINUX9.6:CLSA-2026:1793267498)

critical Nessus Plugin ID 373619

Synopsis

The AlmaLinux host is missing one or more security updates.

Description

The AlmaLinux 9.6 host has packages installed that are affected by multiple vulnerabilities as referenced in the TuxCare ALMALINUX9.6:CLSA-2026:1793267498 advisory.

- Passing an effectively empty string to the `,ccs=` syntax extension of the mode argument in the `fopen` function in the GNU C Library version 2.45 or earlier may result in a heap buffer overflow when the mode string input to the function is attacker controlled. This usage pattern is not seen in applications in common GNU/Linux distributions and applications that process user-supplied values for `ccs` should not pass them through without validation. (CVE-2026-18374)

- Calling tdelete on a sufficiently deep tree in the GNU C Library version 2.1 to 2.44 may write one pointer past the end of an alloca-allocated array on the stack, which may crash the application. The tdelete implementation keeps an explicit stack of parent nodes for rebalancing, which is grown as needed while descending the tree. Two rebalancing branches push an additional entry without checking the capacity, and write past the array when the stack is exactly full. Triggering this requires a node at a depth of exactly 40 (or 40 plus a multiple of 20), which implies a tree with at least a million nodes, so an attacker must drive a large number of insertions and deletions through an application that uses tsearch and tdelete. The written value is a pointer into a tree node and is not directly attacker controlled. No affected application in common distributions has been identified. (CVE-2026-19542)

- Calling wordexp with WRDE_APPEND in the GNU C Library version 2.0 to version 2.43 can cause the interface to return invalid memory in the we_wordv member, which on subsequent calls to wordfree may abort the process. (CVE-2026-6368)

- When expanding paths that begin with a tilde (~) followed by a username, the internal parse_tilde function extracts the username to determine the user's home directory. The implementation allocates memory for this username directly on the stack using the strndupa macro. Because the size of this allocation was determined by the length of the user-supplied input without any bounds checks, passing an excessively long username e.g. thousands of characters, forces the thread to exhaust its stack space. Thus if an application passes untrusted, attacker-controlled input to the wordexp function, an attacker can trigger a stack clash. (CVE-2026-6791)

- Converting crafted SHIFT_JISX0213 input to UCS-4 or the internal wide character encoding, for example with iconv, in the GNU C Library version 2.3 to 2.44 may result in the converter making no progress, causing the calling application to hang. Some SHIFT_JISX0213 sequences decode to two code points. If the output buffer has room for only the first one, the converter stores the second in the conversion state and returns E2BIG, but it never clears that pending character after emitting it on the next call. The converter then keeps emitting the pending character without consuming further input, so an application that retries the conversion loops forever. The input must be attacker controlled and the application must convert it with an output buffer small enough to split the two code points. Only the SHIFT_JISX0213 character set is affected, which is not commonly used. The related defect in the EUC_JISX0213 converter is tracked separately as CVE-2026-80489. (CVE-2026-77117)

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-2026:1793267498.

Plugin Details

Severity: Critical

ID: 373619

File Name: tuxcare_alma_linux_9.6_CLSA-2026-1793267498.nasl

Version: 1.1

Type: Local

Family: Alma Linux Local Security Checks

Published: 10/29/2026

Updated: 10/29/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Risk Information

VPR

Risk Factor: Low

Score: 3

Percentile: 23.68

Vendor

Vendor Severity: Moderate

CVSS v2

Risk Factor: Medium

Base Score: 5.7

Temporal Score: 4.2

Vector: CVSS2#AV:L/AC:L/Au:S/C:P/I:P/A:C

CVSS Score Source: CVE-2026-6791

CVSS v3

Risk Factor: Medium

Base Score: 5.6

Temporal Score: 4.9

Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

CVSS Score Source: CVE-2026-19542

CVSS v4

Risk Factor: Critical

Base Score: 9

Threat Score: 6.6

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:L/SA:H

Vulnerability Information

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/AlmaLinux/release, Host/AlmaLinux/rpm-list, Host/OS/extended-third-party

Exploit Ease: No known exploits are available

Patch Publication Date: 10/29/2026

Vulnerability Publication Date: 8/10/2026

Reference Information

CVE: CVE-2026-18374, CVE-2026-19542, CVE-2026-6368, CVE-2026-6791, CVE-2026-77117, CVE-2026-80489

CLSA: 2026:1793267498

Detections

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