CVE-2026-39856

Process crash via unvalidated PE section bounds

Published Apr 9, 2026 · Updated Apr 9, 2026

Out-of-bounds read in osslsigncode before 2.13 allows attackers to crash the process through a crafted PE file during page hashing. pe_page_hash_calc() trusts section-header PointerToRawData and SizeOfRawData values and hashes beyond the mapped file without checking their bounds. Signing requires page hashing to be enabled, while verification reaches the flaw when the malicious signed file already contains page hashes.

CVSS severity5.5
Medium
EPSS probability0.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds read in osslsigncode before 2.13 allows attackers to crash the process through a crafted PE file during page hashing. pe_page_hash_calc() trusts section-header PointerToRawData and SizeOfRawData values and hashes beyond the mapped file without checking their bounds. Signing requires page hashing to be enabled, while verification reaches the flaw when the malicious signed file already contains page hashes.

The record

CVE
CVE-2026-39856
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
Michał Trojnara
Product
osslsigncode
Classifications
CWE-20, CWE-125, T1204.002
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 9, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 9, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 2.13

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Michał Trojnara · osslsigncodeversion=< 2.13

Published CVSS scores

5.5GitHubCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-20Improper Input Validation
CWE-125Out-of-bounds Read
T1204.002User Execution: Malicious File

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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