CVE-2021-23543Public exploitNetwork attack vector

Sandbox escape via stack-trace prototype pollution

Published Jan 7, 2022 · Updated Sep 16, 2024

Prototype pollution in all Agoric realms-shim versions allows context-dependent attackers to escape Realm sandboxes through crafted code. Evaluated code traverses an exposed Error object's prototype chain and triggers stack construction to write a property into the host realm. Exploitation requires a consuming application to evaluate attacker-controlled code, after which host object prototypes can be modified.

CVSS severity9.8
Critical
EPSS probability1.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Prototype pollution in all Agoric realms-shim versions allows context-dependent attackers to escape Realm sandboxes through crafted code. Evaluated code traverses an exposed Error object's prototype chain and triggers stack construction to write a property into the host realm. Exploitation requires a consuming application to evaluate attacker-controlled code, after which host object prototypes can be modified.

The record

CVE
CVE-2021-23543
Published
Jan 7, 2022
Updated
Sep 16, 2024
Vendor
Agoric
Product
realms-shim
Classifications
CWE-1321
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 7, 2022CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=0 <unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Agoric · realms-shimversion=0 <unspecified

Published CVSS scores

9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.8SnykCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.3Snyk CNACVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E: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-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

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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