CVE-2022-40138Network attack vector

Arbitrary code execution via truncated bytecode operand

Published Oct 11, 2022 · Updated Aug 3, 2024

Integer conversion in Meta Platforms, Inc. Hermes allows remote attackers to execute arbitrary code via untrusted JavaScript input. HBC bytecode emission narrowed an environment-depth operand to uint8_t without rejecting values above 255, producing malformed bytecode. Exploitation requires an embedding that passes attacker-controlled JavaScript to Hermes; ordinary React Native applications generally do not expose that path.

CVSS severity9.8
Critical
EPSS probability0.98%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer conversion in Meta Platforms, Inc. Hermes allows remote attackers to execute arbitrary code via untrusted JavaScript input. HBC bytecode emission narrowed an environment-depth operand to uint8_t without rejecting values above 255, producing malformed bytecode. Exploitation requires an embedding that passes attacker-controlled JavaScript to Hermes; ordinary React Native applications generally do not expose that path.

The record

CVE
CVE-2022-40138
Published
Oct 11, 2022
Updated
Aug 3, 2024
Vendor
Meta Platforms, Inc.
Product
Hermes
Classifications
CWE-681, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 11, 2022CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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?

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

  1. Affected versionversion=unspecified <commit prior to 6aa825e480d48127b480b08d13adf70033237097

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Meta Platforms, Inc. · Hermesversion=unspecified <commit prior to 6aa825e480d48127b480b08d13adf70033237097

Published CVSS scores

9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

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

Weakness, pattern, technique

CWE-681Incorrect Conversion between Numeric Types
T1203Exploitation for Client Execution

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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