CVE-2026-4177 Memory corruption in YAML::Syck
Heap buffer overflow and memory corruption in YAML::Syck allow attackers to execute code or cause denial of service via crafted YAML input.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-4177?
CVE-2026-4177 is a critical memory corruption vulnerability in TODDR YAML::Syck, published on 16 Mar 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
YAML::Syck versions through 1.36 for Perl has several potential security vulnerabilities including a high-severity heap buffer overflow in the YAML emitter.
The heap overflow occurs when class names exceed the initial 512-byte allocation.
The base64 decoder could read past the buffer end on trailing newlines.
strtok mutated n->type_id in place, corrupting shared node data.
A memory leak occurred in syck_hdlr_add_anchor when a node already had an anchor. The incoming anchor string 'a' was leaked on early return.
Which versions are affected by CVE-2026-4177?
It affects 1 product.
Linux distribution packages (8)
perl-YAML-Syck AlmaLinux:8 | All versions | 1.30-6.el8_10 |
perl-YAML-Syck Red Hat:enterprise_linux:8::crb | All versions | 0:1.30-6.el8_10 |
perl-YAML-Syck-debuginfo Red Hat:enterprise_linux:8::crb | All versions | 0:1.30-6.el8_10 |
perl-YAML-Syck-debugsource Red Hat:enterprise_linux:8::crb | All versions | 0:1.30-6.el8_10 |
perl-YAML-Syck Red Hat:rhel_els:7 | All versions | 0:1.27-3.el7_9.1 |
perl-YAML-Syck-debuginfo Red Hat:rhel_els:7 | All versions | 0:1.27-3.el7_9.1 |
perl-YAML-Syck Rocky Linux:8 | All versions | 0:1.30-6.el8_10 |
perl-YAML-Syck openSUSE:Tumbleweed | All versions | 1.440.0-1.1 |
Products include Toddr Yaml\.
How do I fix CVE-2026-4177?
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-2026-4177 being exploited?
There is no known exploitation of CVE-2026-4177 in the wild and no public exploit code.
Other vulnerabilities in TODDR YAML::Syck
Sources
Also known as ALPINE-CVE-2026-4177, ALSA-2026:6470, AZL-109508, AZL-79977, BELL-CVE-2026-4177, DEBIAN-CVE-2026-4177 and 8 more.