CVE-2023-27371 Denial of service in n/a

Medium 5.9 Published 28 Feb 2023 Updated 14 Oct 2026

Remote attackers can cause a denial of service in applications using libmicrohttpd by sending malicious HTTP POST packets with null bytes in multipart boundaries.

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

What is CVE-2023-27371?

CVE-2023-27371 is a medium-severity denial of service vulnerability in n/a, published on 28 Feb 2023. An attacker can exploit it over the internet without logging in, with no action from the victim.

Official description

GNU libmicrohttpd before 0.9.76 allows remote DoS (Denial of Service) due to improper parsing of a multipart/form-data boundary in the postprocessor.c MHD_create_post_processor() method. This allows an attacker to remotely send a malicious HTTP POST packet that includes one or more '\0' bytes in a multipart/form-data boundary field, which - assuming a specific heap layout - will result in an out-of-bounds read and a crash in the find_boundary() function.

Weakness: CWE-125

Which versions are affected by CVE-2023-27371?

It affects 1 product.

Linux distribution packages (40)

`libmicrohttpd` AlmaLinux:8	All versions	`1:0.9.59-3.el8`
`libmicrohttpd-devel` AlmaLinux:8	All versions	`1:0.9.59-3.el8`
`libmicrohttpd-doc` AlmaLinux:8	All versions	`1:0.9.59-3.el8`
`libmicrohttpd` AlmaLinux:9	All versions	`1:0.9.72-5.el9`
`libmicrohttpd-devel` AlmaLinux:9	All versions	`1:0.9.72-5.el9`
`libmicrohttpd-doc` AlmaLinux:9	All versions	`1:0.9.72-5.el9`
`libmicrohttpd` Red Hat:enterprise_linux:8::baseos	All versions	`1:0.9.59-3.el8`
`libmicrohttpd-debuginfo` Red Hat:enterprise_linux:8::baseos	All versions	`1:0.9.59-3.el8`
`libmicrohttpd-debugsource` Red Hat:enterprise_linux:8::baseos	All versions	`1:0.9.59-3.el8`
`libmicrohttpd-debuginfo` Red Hat:enterprise_linux:8::crb	All versions	`1:0.9.59-3.el8`
`libmicrohttpd-debugsource` Red Hat:enterprise_linux:8::crb	All versions	`1:0.9.59-3.el8`
`libmicrohttpd-devel` Red Hat:enterprise_linux:8::crb	All versions	`1:0.9.59-3.el8`
`libmicrohttpd-doc` Red Hat:enterprise_linux:8::crb	All versions	`1:0.9.59-3.el8`
`libmicrohttpd` Red Hat:enterprise_linux:9::appstream	All versions	`1:0.9.72-5.el9`
`libmicrohttpd-debuginfo` Red Hat:enterprise_linux:9::appstream	All versions	`1:0.9.72-5.el9`
`libmicrohttpd-debugsource` Red Hat:enterprise_linux:9::appstream	All versions	`1:0.9.72-5.el9`
`libmicrohttpd-debuginfo` Red Hat:enterprise_linux:9::crb	All versions	`1:0.9.72-5.el9`
`libmicrohttpd-debugsource` Red Hat:enterprise_linux:9::crb	All versions	`1:0.9.72-5.el9`
`libmicrohttpd-devel` Red Hat:enterprise_linux:9::crb	All versions	`1:0.9.72-5.el9`
`libmicrohttpd-doc` Red Hat:enterprise_linux:9::crb	All versions	`1:0.9.72-5.el9`
`libmicrohttpd` Red Hat:rhel_eus:8.6::baseos	All versions	`1:0.9.59-2.el8_6.1`
`libmicrohttpd-debuginfo` Red Hat:rhel_eus:8.6::baseos	All versions	`1:0.9.59-2.el8_6.1`
`libmicrohttpd-debugsource` Red Hat:rhel_eus:8.6::baseos	All versions	`1:0.9.59-2.el8_6.1`
`libmicrohttpd-debuginfo` Red Hat:rhel_eus:8.6::crb	All versions	`1:0.9.59-2.el8_6.1`
`libmicrohttpd-debugsource` Red Hat:rhel_eus:8.6::crb	All versions	`1:0.9.59-2.el8_6.1`
`libmicrohttpd-devel` Red Hat:rhel_eus:8.6::crb	All versions	`1:0.9.59-2.el8_6.1`
`libmicrohttpd-doc` Red Hat:rhel_eus:8.6::crb	All versions	`1:0.9.59-2.el8_6.1`
`libmicrohttpd` Red Hat:rhel_eus:8.8::baseos	All versions	`1:0.9.59-2.el8_8.1`
`libmicrohttpd-debuginfo` Red Hat:rhel_eus:8.8::baseos	All versions	`1:0.9.59-2.el8_8.1`
`libmicrohttpd-debugsource` Red Hat:rhel_eus:8.8::baseos	All versions	`1:0.9.59-2.el8_8.1`
`libmicrohttpd-debuginfo` Red Hat:rhel_eus:8.8::crb	All versions	`1:0.9.59-2.el8_8.1`
`libmicrohttpd-debugsource` Red Hat:rhel_eus:8.8::crb	All versions	`1:0.9.59-2.el8_8.1`
`libmicrohttpd-devel` Red Hat:rhel_eus:8.8::crb	All versions	`1:0.9.59-2.el8_8.1`
`libmicrohttpd-doc` Red Hat:rhel_eus:8.8::crb	All versions	`1:0.9.59-2.el8_8.1`
`libmicrohttpd` Rocky Linux:8	All versions	`1:0.9.59-3.el8`
`libmicrohttpd` Rocky Linux:9	All versions	`1:0.9.72-5.el9`
`libmicrohttpd` SUSE:Linux Enterprise Micro 5.1	All versions	`0.9.57-150000.3.3.1`
`libmicrohttpd` SUSE:Linux Enterprise Micro 5.2	All versions	`0.9.57-150000.3.3.1`
`libmicrohttpd` SUSE:Linux Enterprise Micro 5.3	All versions	`0.9.57-150000.3.3.1`
`libmicrohttpd` SUSE:Linux Enterprise Micro 5.4	All versions	`0.9.57-150000.3.3.1`

Products include Gnu Libmicrohttpd.

How do I fix CVE-2023-27371?

Upgrade to a fixed version.

Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.

Is CVE-2023-27371 being exploited?

There is no known exploitation of CVE-2023-27371 in the wild and no public exploit code.

Sources

Also known as ALSA-2023:6566, ALSA-2023:7090, AZL-25347, CLSA-2025-1760026053, DEBIAN-CVE-2023-27371, DLA-3374-1 and 14 more.