CVE-2026-25920 | SumatraPDF has a heap out-of-bounds read in MOBI HuffDic decompressor

Exp

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.

Published: 2026-02-09 Last update: 2026-06-17 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-25920 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.22%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-25920

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-25920

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-06-15 0.01% 0.22% +0.21%
2 2026-02-10 — 0.01% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-25920

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:R)
A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 1.8 3.6 [email protected]

Weakness enumeration for CVE-2026-25920

Affected software / configurations for CVE-2026-25920

Vendor Product Version Raw CPE
sumatrapdfreader sumatrapdf <= 3.5.2 cpe:2.3:a:sumatrapdfreader:sumatrapdf:*:*:*:*:*:*:*:*

References for CVE-2026-25920

cvelogic Threat Intelligence