Stack buffer overflow in CFF to Type 1 font conversion
Summary
| CVE | CVE-2026-63276 |
|---|---|
| State | PUBLISHED |
| Assigner | Document Fdn. |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-22 12:17:13 UTC |
| Updated | 2026-09-22 19:09:32 UTC |
| Description | LibreOffice converts CFF fonts to Type 1 when it subsets a font, which happens when a document is exported to PDF, and CFF fonts may be embedded in documents. A stack buffer overflow existed in that conversion. The converted operators were written into a fixed size buffer with no check that they still fit, so a glyph emitting many operators wrote past the end of the buffer. In fixed versions the remaining capacity is tracked and the conversion stops when it is used up. |
Risk And Classification
Primary CVSS: v4.0 5.4 MEDIUM from [email protected]
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.001670000 probability, percentile 0.063970000 (date 2026-09-23)
Problem Types: CWE-787 | CWE-787 CWE-787 Out-of-bounds Write
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 5.4 | MEDIUM | CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:P/C... |
| 4.0 | CNA | CVSS | 5.4 | MEDIUM | CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:P |
CVSS v4.0 Breakdown
Attack Vector
LocalAttack Complexity
LowAttack Requirements
NonePrivileges Required
NoneUser Interaction
PassiveConfidentiality
LowIntegrity
LowAvailability
HighSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | The Document Foundation | LibreOffice | affected 26.2 < 26.2.5 26.2 series | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| www.libreoffice.org/about-us/security/advisories/cve-2026-63276 | [email protected] | www.libreoffice.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Claude, found by Anthropic using agents to study the security of open-source projects (en)
CNA: Ada Logics, validating and reporting (en)
CNA: Caolán McNamara of Collabora Productivity (en)
There are currently no legacy QID mappings associated with this CVE.