CVE-2021-3826 Memory corruption in gcc

Medium 6.5 Published 1 Sep 2022 Updated 14 Oct 2026

Attackers can cause a denial of service via a crafted mangled symbol triggering a buffer overflow in the libiberty demangling function.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: A user has to click or open something
Fix: Available

What is CVE-2021-3826?

CVE-2021-3826 is a medium-severity memory corruption vulnerability in Fedoraproject Fedora, published on 1 Sep 2022. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

Official description

Heap/stack buffer overflow in the dlang_lname function in d-demangle.c in libiberty allows attackers to potentially cause a denial of service (segmentation fault and crash) via a crafted mangled symbol.

Weakness: CWE-787, CWE-119

Which versions are affected by CVE-2021-3826?

It affects 2 products.

Linux distribution packages (12)

`gdb` AlmaLinux:9	All versions	`10.2-11.el9`
`gdb-doc` AlmaLinux:9	All versions	`10.2-11.el9`
`gdb-gdbserver` AlmaLinux:9	All versions	`10.2-11.el9`
`gdb-headless` AlmaLinux:9	All versions	`10.2-11.el9`
`gdb-minimal` AlmaLinux:9	All versions	`10.2-11.el9`
`gdb` Red Hat:enterprise_linux:9::appstream	All versions	`0:10.2-11.el9`
`gdb-debuginfo` Red Hat:enterprise_linux:9::appstream	All versions	`0:10.2-11.el9`
`gdb-debugsource` Red Hat:enterprise_linux:9::appstream	All versions	`0:10.2-11.el9`
`gdb-doc` Red Hat:enterprise_linux:9::appstream	All versions	`0:10.2-11.el9`
`gdb-gdbserver` Red Hat:enterprise_linux:9::appstream	All versions	`0:10.2-11.el9`
`gdb-headless` Red Hat:enterprise_linux:9::appstream	All versions	`0:10.2-11.el9`
`gdb-minimal` Red Hat:enterprise_linux:9::appstream	All versions	`0:10.2-11.el9`

Products include Fedoraproject Fedora, Gnu Gcc.

How do I fix CVE-2021-3826?

Apply the vendor's patch.

Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.

Is CVE-2021-3826 being exploited?

There is no known exploitation of CVE-2021-3826 in the wild and no public exploit code.

All Fedoraproject Fedora vulnerabilities

Sources

Also known as ALSA-2023:6372, CLSA-2024-1718787131, CLSA-2026-1777465067, CLSA-2026-1778020045, CLSA-2026-1780133935, DEBIAN-CVE-2021-3826 and 3 more.