OSV-2026-777 Heap-buffer-overflow in md_is_link_title
A heap buffer overflow in the markdown parser allows attackers to cause denial of service or potentially execute code via crafted input.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is OSV-2026-777?
OSV-2026-777 is a memory corruption vulnerability in md4c, published on 19 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=514122612
Crash type: Heap-buffer-overflow READ 1
Crash state:
md_is_link_title
md_analyze_inlines
md_process_normal_block_contents
Which versions are affected by OSV-2026-777?
1 open source package ship an affected version, including md4c.
| Package | Affected | Fixed in |
|---|---|---|
md4c OSS-Fuzz | All versions | None |
How do I fix OSV-2026-777?
No fix has been published for OSV-2026-777 yet. Limit exposure of the affected software until one is available.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is OSV-2026-777 being exploited?
There is no known exploitation of OSV-2026-777 in the wild and no public exploit code.