CVE-2026-63276: the document foundation libreoffice Out-of-bounds Write
Vulnerability summary
CVE-2026-63276 is a medium (CVSS 5.4) Out-of-bounds Write vulnerability in the document foundation libreoffice. EPSS estimates a 0.19% chance of exploitation in the next 30 days, higher than 8.6% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 3 · Related 1Timeline
- 22-09-2026PublishedVulnerability first disclosed.
- 22-09-2026Last modifiedVulnerability information updated.
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.
CVSS metrics
4 scores · 4 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated6.9MediumCVSS: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:PDiffers
- OSV · DebianEcosystem advisory · calculated6.9MediumCVSS: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:XDiffers
- NVDNIST5.4MediumCVSS: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 trend
Probability
0.19%
Chance of exploitation in the next 30 days
Percentile
9%
Versus all other CVEs
30-day change
Change unavailable
Change unavailable
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Debian1 product
- libreofficeAll versions (No fix recorded) | < 4:25.2.3-2+deb13u7 | < 4:26.2.5.2-1
The document foundation1 product
- libreoffice≥ 26.2, < < 26.2.5
Ubuntu1 product
- libreofficeAll versions (No fix recorded) | < 1:7.3.7-0ubuntu0.22.04.13 | < 4:24.2.7-0ubuntu0.24.04.7 | < 4:26.2.6.3-0ubuntu0.26.04.2
3 vendors · 3 products
