CVE-2020-1896Public exploitNetwork attack vector

Code execution via unchecked apply call frame

Published Feb 2, 2021 · Updated Aug 4, 2024

Stack overflow in builtin apply in Meta Platforms Hermes allows attackers to execute arbitrary code via crafted JavaScript. The hermesBuiltinApply function creates a native call frame from the argument count but fails to test whether that frame overflowed before copying arguments into it. Exploitation requires an application that evaluates untrusted JavaScript; most React Native applications do not expose that condition.

CVSS severity9.8
Critical
EPSS probability2.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack overflow in builtin apply in Meta Platforms Hermes allows attackers to execute arbitrary code via crafted JavaScript. The hermesBuiltinApply function creates a native call frame from the argument count but fails to test whether that frame overflowed before copying arguments into it. Exploitation requires an application that evaluates untrusted JavaScript; most React Native applications do not expose that condition.

The record

CVE
CVE-2020-1896
Published
Feb 2, 2021
Updated
Aug 4, 2024
Vendor
Meta Platforms, Inc.
Product
Hermes
Classifications
CWE-787, CWE-121, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 2, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=commit prior to 86543ac47e59c522976b5632b8bf9a2a4583c7d2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Meta Platforms, Inc. · Hermesversion=commit prior to 86543ac47e59c522976b5632b8bf9a2a4583c7d2

Published CVSS scores

9.8NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
6.8NVDAV:N/AC:M/Au:N/C:P/I:P/A:P

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 exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
CWE-121Stack-based Buffer Overflow
T1203Exploitation for Client Execution

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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