CVE-2025-62491

Memory corruption via reentrant promise rejection handling

Published Oct 16, 2025 · Updated Oct 16, 2025

Use-after-free in QuickJS 2025-04-26 allows attackers to corrupt process memory by supplying a crafted rejected promise. While js_std_promise_rejection_check dumps an Error reason, a custom getter can attach catch() to the same promise, freeing the current list entry during iteration. Execution of attacker-controlled JavaScript with a crafted Error getter is required; continued traversal then dereferences the freed entry, enabling process memory corruption or a crash.

CVSS severity8.8
High
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use-after-free in QuickJS 2025-04-26 allows attackers to corrupt process memory by supplying a crafted rejected promise. While js_std_promise_rejection_check dumps an Error reason, a custom getter can attach catch() to the same promise, freeing the current list entry during iteration. Execution of attacker-controlled JavaScript with a crafted Error getter is required; continued traversal then dereferences the freed entry, enabling process memory corruption or a crash.

The record

CVE
CVE-2025-62491
Published
Oct 16, 2025
Updated
Oct 16, 2025
Vendor
Fabrice Bellard
Product
QuickJS
Classifications
CWE-416
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Oct 16, 2025CVE publishedPublication date reported by the CVE source.
  2. Oct 16, 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?

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  1. Affected versionversion=2025-04-26 <2025-09-13

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Fabrice Bellard · QuickJSversion=2025-04-26 <2025-09-13

Published CVSS scores

8.8Google Inc.CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L
8.8NIST NVDCVSS:3.1/AV:A/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.

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No observations available

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

Weakness, pattern, technique

CWE-416Use After Free

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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