Stack-based buffer overflow in HarfBuzz - #VU128344
Published: April 28, 2026
Vulnerability identifier: #VU128344
CSH Severity: Medium
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: N/A
CWE-ID: CWE-121
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Freedesktop.org
Affected software:
HarfBuzz
HarfBuzz
Detailed vulnerability description
The vulnerability allows a remote attacker to overwrite other data.
The vulnerability exists due to a stack-based buffer overflow in debug messaging in Sequence.hh when processing a maliciously crafted OpenType font with a GSUB sequence lookup. A remote attacker can supply a crafted font that injects a large number of glyphs to overwrite other data.
The issue is reachable only when debug messaging is enabled using hb_buffer_set_message_func.
Remediation
Install security update from vendor's website.