How severe is CVE-2026-25920?

CVE-2026-25920 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-25920 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-25920?

CVE-2026-25920 affects Sumatrapdfreader Sumatrapdf. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-25920?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-25920 have an EU (EUVD) identifier?

Yes. CVE-2026-25920 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6260.

When was CVE-2026-25920 published?

CVE-2026-25920 was published on 2026-02-09 and last updated on 2026-06-17.

CVE-2026-25920

CVE-2026-25920 is a medium-severity vulnerability in Sumatrapdfreader Sumatrapdf with a CVSS 3.x base score of 5.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-125.

Key facts

Severity: Medium (CVSS 3.x base score 5.5)
EPSS exploit prediction: 0% (12th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-6260
Weakness: CWE-125
Affected product: Sumatrapdfreader Sumatrapdf
Published: 2026-02-09
Last modified: 2026-06-17

Description

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.

Frequently asked questions

What is CVE-2026-25920?: 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.
How severe is CVE-2026-25920?: CVE-2026-25920 has a CVSS 3.x base score of 5.5, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-25920 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (12th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-25920?: CVE-2026-25920 affects Sumatrapdfreader Sumatrapdf. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-25920?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-25920 have an EU (EUVD) identifier?: Yes. CVE-2026-25920 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-6260.
When was CVE-2026-25920 published?: CVE-2026-25920 was published on 2026-02-09 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:sumatrapdfreader:sumatrapdf:*:*:*:*:*:*:*:*

More vulnerabilities in Sumatrapdfreader Sumatrapdf

CVE-2012-4896 — Critical (CVSS 9.3): Heap-based buffer overflow in SumatraPDF before 2.1 allows remote attackers to execute arbitrary code via a crafted PDF…
CVE-2012-4895 — Critical (CVSS 9.3): Heap-based buffer overflow in SumatraPDF before 2.1 allows remote attackers to execute arbitrary code via a crafted PDF…
CVE-2009-4117 — Critical (CVSS 9.3): Multiple stack-based buffer overflows in pdf_shade4.c in MuPDF before commit 20091125231942, as used in SumatraPDF…
CVE-2026-23512 — High (CVSS 8.6): SumatraPDF is a multi-format reader for Windows. In 3.5.2 and earlier, there is a Untrusted Search Path vulnerability…
CVE-2026-25880 — High (CVSS 7.8): SumatraPDF is a multi-format reader for Windows. In 3.5.2 and earlier, the PDF reader allows execution of a malicious…
CVE-2012-5340 — High (CVSS 7.8): SumatraPDF 2.1.1/MuPDF 1.0 allows remote attackers to cause an Integer Overflow in the lex_number() function via a…

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Other CWE-125 (Out-of-bounds Read) vulnerabilities

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CVE-2021-21777 — Critical (CVSS 10.0): An information disclosure vulnerability exists in the Ethernet/IP UDP handler functionality of EIP Stack Group OpENer…
CVE-2017-14451 — Critical (CVSS 10.0): An exploitable out-of-bounds read vulnerability exists in libevm (Ethereum Virtual Machine) of CPP-Ethereum. A…
CVE-2013-0767 — Critical (CVSS 10.0): The nsSVGPathElement::GetPathLengthScale function in Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and…

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