CVE-2020-29573 Memory corruption in n/a

High 7.5 Published 5 Dec 2020 Updated 14 Oct 2026

Stack-based buffer overflow in glibc printf functions on x86 allows attackers to execute arbitrary code or cause denial of service via crafted long double inputs.

Exploited in the wild: Not known
Login needed: Not needed
Attackable: Over the internet
Victim action needed: Not needed
Fix: Available

What is CVE-2020-29573?

CVE-2020-29573 is a high-severity memory corruption vulnerability in Gnu Glibc, published on 5 Dec 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

sysdeps/i386/ldbl2mpn.c in the GNU C Library (aka glibc or libc6) before 2.23 on x86 targets has a stack-based buffer overflow if the input to any of the printf family of functions is an 80-bit long double with a non-canonical bit pattern, as seen when passing a \x00\x04\x00\x00\x00\x00\x00\x00\x00\x04 value to sprintf. NOTE: the issue does not affect glibc by default in 2016 or later (i.e., 2.23 or later) because of commits made in 2015 for inlining of C99 math functions through use of GCC built-ins. In other words, the reference to 2.23 is intentional despite the mention of "Fixed for glibc 2.33" in the 26649 reference.

Weakness: CWE-787

Which versions are affected by CVE-2020-29573?

It affects 4 products.

Linux distribution packages (27)

`glibc` Red Hat:rhel_aus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-common` Red Hat:rhel_aus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-debuginfo` Red Hat:rhel_aus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-debuginfo-common` Red Hat:rhel_aus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-devel` Red Hat:rhel_aus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-headers` Red Hat:rhel_aus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-static` Red Hat:rhel_aus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-utils` Red Hat:rhel_aus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`nscd` Red Hat:rhel_aus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc` Red Hat:rhel_e4s:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-common` Red Hat:rhel_e4s:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-debuginfo` Red Hat:rhel_e4s:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-debuginfo-common` Red Hat:rhel_e4s:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-devel` Red Hat:rhel_e4s:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-headers` Red Hat:rhel_e4s:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-static` Red Hat:rhel_e4s:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-utils` Red Hat:rhel_e4s:7.4::server	All versions	`0:2.17-196.el7_4.4`
`nscd` Red Hat:rhel_e4s:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc` Red Hat:rhel_tus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-common` Red Hat:rhel_tus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-debuginfo` Red Hat:rhel_tus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-debuginfo-common` Red Hat:rhel_tus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-devel` Red Hat:rhel_tus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-headers` Red Hat:rhel_tus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-static` Red Hat:rhel_tus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`glibc-utils` Red Hat:rhel_tus:7.4::server	All versions	`0:2.17-196.el7_4.4`
`nscd` Red Hat:rhel_tus:7.4::server	All versions	`0:2.17-196.el7_4.4`

Products include Gnu Glibc, Netapp Cloud Backup, Netapp Solidfire Baseboard Management Controller, Redhat Enterprise Linux.

How do I fix CVE-2020-29573?

Upgrade to a fixed version.

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

Is CVE-2020-29573 being exploited?

There is no known exploitation of CVE-2020-29573 in the wild and no public exploit code.

All Gnu Glibc vulnerabilities

Sources

Also known as DEBIAN-CVE-2020-29573, GHSA-x6gp-hg9r-wh46, RHSA-2021:2813, UBUNTU-CVE-2020-29573.