Integer overflow in Chmlib

CVE-2025-48172

CHMLib through 2bef8d0, as used in SumatraPDF and other products, has a chm_lib.c _chm_decompress_block integer overflow. There is a resultant heap-based buffer overflow in _chm_fetch_bytes.

Vulnerability class: Integer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 5.6 (Medium). Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.002 (5.6th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 6th percentile — 5.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2025-48172: held from 0.002 to 0.002.

EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2025-48172?
CVE-2025-48172 is a medium-severity vulnerability in Chmlib, classified under Integer Overflow or Wraparound. CVSS score: 5.6/10. Published 2025-07-04.
How severe is CVE-2025-48172?
Medium severity. CVSS v3 base score is 5.6 out of 10.