CVE-2021-45985Public exploitNetwork attack vector

Process crash via finalizer during tail call

Published Apr 10, 2023 · Updated Feb 12, 2025

Heap-based buffer over-read in Lua 5.4.3 allows attackers to crash an embedding process by triggering a finalizer during a tail call. The luaD_pretailcall function invokes checkstackGC after partially updating CallInfo, so a garbage-collection finalizer observes an inconsistent call stack and an error path reads beyond a heap buffer. Triggering the fault requires execution of crafted Lua code that combines a large tail call with a failing __gc metamethod; the demonstrated consequence is a process crash.

CVSS severity7.5
High
EPSS probability1.42%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap-based buffer over-read in Lua 5.4.3 allows attackers to crash an embedding process by triggering a finalizer during a tail call. The luaD_pretailcall function invokes checkstackGC after partially updating CallInfo, so a garbage-collection finalizer observes an inconsistent call stack and an error path reads beyond a heap buffer. Triggering the fault requires execution of crafted Lua code that combines a large tail call with a failing __gc metamethod; the demonstrated consequence is a process crash.

The record

CVE
CVE-2021-45985
Published
Apr 10, 2023
Updated
Feb 12, 2025
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-787
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 10, 2023CVE publishedPublication date reported by the CVE source.
  2. Feb 12, 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?

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

7.5CISA CoordinatorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5NISTCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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

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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