CVE-2020-18494Public exploitNetwork attack vector

Code execution via unchecked EFL metadata decoding

Published Aug 22, 2023 · Updated Oct 7, 2024

Out-of-bounds write in HDF5 1.10.4 allows remote attackers to execute arbitrary code when a crafted HDF5 file is processed. The upstream fix adds input-buffer bounds checks and validates slot counts while H5O__efl_decode parses external-file-list metadata. Execution requires an application to process attacker-supplied HDF5 content, and the resulting memory corruption runs code in that application's context.

CVSS severity8.8
High
EPSS probability1.01%
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 write in HDF5 1.10.4 allows remote attackers to execute arbitrary code when a crafted HDF5 file is processed. The upstream fix adds input-buffer bounds checks and validates slot counts while H5O__efl_decode parses external-file-list metadata. Execution requires an application to process attacker-supplied HDF5 content, and the resulting memory corruption runs code in that application's context.

The record

CVE
CVE-2020-18494
Published
Aug 22, 2023
Updated
Oct 7, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787, T1204.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 22, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 7, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1204.002User Execution: Malicious File

Public exploit references

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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