CVE-2023-25933Network attack vector

Code execution via untrusted TypedArray value encoding

Published May 18, 2023 · Updated Jan 21, 2025

Type confusion in Meta Platforms Hermes before commit e6ed9c1 allows attackers to execute arbitrary code via untrusted JavaScript. typedArrayPrototypeAt encoded an array element with encodeNumberValue even though a crafted NaN bit pattern was untrusted, allowing its bits to be interpreted as another Hermes value type. Exploitation requires an application to execute attacker-controlled JavaScript; most React Native applications do not expose that condition.

CVSS severity9.8
Critical
EPSS probability0.89%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Type confusion in Meta Platforms Hermes before commit e6ed9c1 allows attackers to execute arbitrary code via untrusted JavaScript. typedArrayPrototypeAt encoded an array element with encodeNumberValue even though a crafted NaN bit pattern was untrusted, allowing its bits to be interpreted as another Hermes value type. Exploitation requires an application to execute attacker-controlled JavaScript; most React Native applications do not expose that condition.

The record

CVE
CVE-2023-25933
Published
May 18, 2023
Updated
Jan 21, 2025
Vendor
Meta Platforms, Inc.
Product
Hermes
Classifications
CWE-843, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 18, 2023CVE publishedPublication date reported by the CVE source.
  2. Jan 21, 2025Record 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=0 <e6ed9c1a4b02dc219de1648f44cd808a56171b81

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Meta Platforms, Inc. · Hermesversion=0 <e6ed9c1a4b02dc219de1648f44cd808a56171b81

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8CISA-ADPCVSS: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-843Access of Resource Using Incompatible Type ('Type Confusion')
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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