CVE-2026-6368: GNU C Library Buffer Overflow Vulnerability

CVE-2026-6368 Overview

CVE-2026-6368 affects the GNU C Library (glibc) versions 2.0 through 2.43. Calling wordexp with the WRDE_APPEND flag can cause the interface to return invalid memory in the we_wordv member. Subsequent calls to wordfree may then abort the process. The flaw is classified as [CWE-908: Use of Uninitialized Resource] and requires local access with high attack complexity to trigger.

Critical Impact
Applications that pass attacker-influenced input through wordexp with WRDE_APPEND may abort during cleanup, producing a localized denial-of-service condition against the calling process.

Affected Products

GNU C Library (glibc) 2.0 through 2.43
Linux distributions bundling affected glibc releases
Applications linking against affected glibc versions that use wordexp

Discovery Timeline

2026-08-10 - CVE-2026-6368 published to NVD
2026-08-12 - Last updated in NVD database

Technical Details for CVE-2026-6368

Vulnerability Analysis

The wordexp function performs shell-style word expansion on a string and returns results through a wordexp_t structure. The we_wordv member holds the expanded word array. When applications set the WRDE_APPEND flag, wordexp is expected to append new results to an existing we_wordv array rather than allocating a fresh one.

In glibc 2.0 through 2.43, the append path can leave we_wordv referencing invalid memory. The pointer state is inconsistent with the accompanying length and offset fields. Because the corruption sits inside the returned structure, the calling program has no reliable way to detect the invalid state before invoking wordfree.

When the application later calls wordfree on that structure, glibc attempts to release the invalid pointer. The result is typically a process abort through the allocator's consistency checks. The failure occurs inside library cleanup, so the calling application cannot recover cleanly.

Root Cause

The root cause is uninitialized or improperly initialized resource handling inside the WRDE_APPEND code path of wordexp. The function leaves the we_wordv field in a state that does not match the invariants expected by wordfree, matching the [CWE-908] weakness pattern.

Attack Vector

Exploitation requires local access and high attack complexity. An attacker must influence input passed to a program that calls wordexp with WRDE_APPEND and subsequently calls wordfree. The realistic impact is a denial-of-service abort of the affected process. The vulnerability does not provide a direct path to code execution or privilege escalation.

No public exploit code, proof-of-concept, or evidence of exploitation in the wild has been reported. The issue is not listed in the CISA Known Exploited Vulnerabilities catalog.

Refer to the Sourceware GLIBC Security Advisory and the Sourceware Bug Report #34090 for upstream technical details.

Detection Methods for CVE-2026-6368

Indicators of Compromise

Unexpected SIGABRT terminations in processes that call wordexp and wordfree
Core dumps referencing glibc allocator abort routines such as malloc_printerr triggered from wordfree
Repeated crashes in shell-adjacent utilities or scripting engines after input processing

Detection Strategies

Inventory installed glibc versions across Linux fleets and flag any release from 2.0 through 2.43
Identify binaries that link wordexp/wordfree symbols using nm, objdump, or ldd-based tooling
Correlate abort signals with the calling process to identify glibc-driven cleanup failures

Monitoring Recommendations

Ship crash telemetry, including signal codes and stack traces, to a centralized log store for pattern detection
Alert on repeated aborts originating from the same binary within short time windows
Track glibc package versions during patch compliance reporting to confirm remediation coverage

How to Mitigate CVE-2026-6368

Immediate Actions Required

Apply the glibc security update referenced in GLIBC-SA-2026-0014 once your distribution ships it
Review internal code for use of wordexp with the WRDE_APPEND flag and validate input handling
Prioritize patching on multi-user hosts and systems that process untrusted local input

Patch Information

Upstream tracking is available in Sourceware Bug #34090. Apply the fixed glibc package provided by your Linux distribution vendor when it becomes available. Restart affected services after upgrading to ensure the patched library is loaded.

Workarounds

Avoid calling wordexp with WRDE_APPEND; allocate a fresh wordexp_t structure per invocation and merge results in application code
Validate and constrain input strings passed to wordexp to limit attacker-controlled expansion
Wrap wordexp usage in isolated helper processes so an abort does not terminate the primary service

bash

# Verify installed glibc version on Debian/Ubuntu
dpkg -l libc6 | awk '/libc6/ {print $2, $3}'

# Verify installed glibc version on RHEL/Fedora
rpm -q glibc

# Locate binaries that reference wordexp on a host
grep -rlZ --include='*' 'wordexp' /usr/bin /usr/sbin 2>/dev/null | xargs -0 -r file