CVE-2026-39855

Process crash via PE page-hash integer underflow

Published Apr 9, 2026 · Updated Apr 9, 2026

Integer underflow in osslsigncode before 2.13 allows attackers to crash the process via a malicious PE file during page-hash processing. The pe_page_hash_calc() function subtracts an attacker-controlled SizeOfHeaders value from SectionAlignment without checking their order, then hashes the wrapped unsigned length from a smaller heap buffer. A user must sign the file with page hashing enabled or verify a signed file containing page hashes; verification needs no page-hash option.

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

Integer underflow in osslsigncode before 2.13 allows attackers to crash the process via a malicious PE file during page-hash processing. The pe_page_hash_calc() function subtracts an attacker-controlled SizeOfHeaders value from SectionAlignment without checking their order, then hashes the wrapped unsigned length from a smaller heap buffer. A user must sign the file with page hashing enabled or verify a signed file containing page hashes; verification needs no page-hash option.

The record

CVE
CVE-2026-39855
Published
Apr 9, 2026
Updated
Apr 9, 2026
Vendor
Michał Trojnara
Product
osslsigncode
Classifications
CWE-125, CWE-190, CWE-191, 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

5.5GitHub, Inc.CVSS: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-125Out-of-bounds Read
CWE-190Integer Overflow or Wraparound
CWE-191Integer Underflow (Wrap or Wraparound)
T1204.002Malicious File

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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