CVE-2026-25920: SumatraPDF has a heap out-of-bounds read in MOBI HuffDic decompressor
SumatraPDF is a multi-format reader for Windows. In 3.5.2 and earlier, a heap out-of-bounds read vulnerability exists in SumatraPDF's MOBI HuffDic decompressor. The bounds check in AddCdicData() only validates half the range that DecodeOne() actually accesses. Opening a crafted .mobi file can read nearly (1 << codeLength) bytes beyond the CDIC dictionary buffer, leading to a crash.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-25920?
CVE-2026-25920 has a high severity due to the potential for exploitation via a heap out-of-bounds read in SumatraPDF.
How do I fix CVE-2026-25920?
To fix CVE-2026-25920, upgrade SumatraPDF to version 3.5.3 or later where the vulnerability has been addressed.
What versions of SumatraPDF are affected by CVE-2026-25920?
CVE-2026-25920 affects all versions of SumatraPDF up to and including version 3.5.2.
What type of vulnerability is CVE-2026-25920?
CVE-2026-25920 is classified as a heap out-of-bounds read vulnerability.
Can CVE-2026-25920 be exploited remotely?
Yes, CVE-2026-25920 can potentially be exploited remotely through crafted MOBI files.