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CVE-2025-62491

Use-after-free in js_std_promise_rejection_check in QuickJS

8.8 High

A Use-After-Free (UAF) vulnerability exists in the QuickJS engine's standard library when iterating over the global list of unhandled rejected promises (ts->rejected_promise_list).

  • The function js_std_promise_rejection_check attempts to iterate over the rejected_promise_list to report unhandled rejections using a standard list loop.

  • The reason for a promise rejection is processed inside the loop, including calling js_std_dump_error1(ctx, rp->reason).

  • If the promise rejection reason is an Error object that defines a custom property getter (e.g., via Object.defineProperty), this getter is executed during the error dumping process.

  • The malicious custom getter can execute JavaScript code that calls catch() on the same rejected promise being processed.

  • Calling catch() internally triggers js_std_promise_rejection_tracker, which then removes and frees the current promise entry (JSRejectedPromiseEntry) from the rejected_promise_list.

  • Since the list iteration continues using the now-freed memory pointer (el), the subsequent loop access results in a Use-After-Free condition.

Attack profile

How easy it is to exploit

Attack vector
Adjacent network
Complexity
High
Privileges needed
None
User interaction
Passive

What an attacker can affect

Confidentiality
High
Integrity
High
Availability
Low

Exploit likelihood

0.41%Up 0.4 points since Oct 17, 2025
90%50%10%1%

What each source reports

CVE List Score used 8.8

Use-after-free in js_std_promise_rejection_check in QuickJS

A Use-After-Free (UAF) vulnerability exists in the QuickJS engine's standard library when iterating over the global list of unhandled rejected promises (ts->rejected_promise_list).

  • The function js_std_promise_rejection_check attempts to iterate over the rejected_promise_list to report unhandled rejections using a standard list loop.

  • The reason for a promise rejection is processed inside the loop, including calling js_std_dump_error1(ctx, rp->reason).

  • If the promise rejection reason is an Error object that defines a custom property getter (e.g., via Object.defineProperty), this getter is executed during the error dumping process.

  • The malicious custom getter can execute JavaScript code that calls catch() on the same rejected promise being processed.

  • Calling catch() internally triggers js_std_promise_rejection_tracker, which then removes and frees the current promise entry (JSRejectedPromiseEntry) from the rejected_promise_list.

  • Since the list iteration continues using the now-freed memory pointer (el), the subsequent loop access results in a Use-After-Free condition.

Record
CVE-2025-62491
CVSS 4.0
8.8 HighCVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L
Weakness
CWE-416
Updated
2026-11-02
EUVDEUVD-2025-34783 8.8

A Use-After-Free (UAF) vulnerability exists in the QuickJS engine's standard library when iterating over the global list of unhandled rejected promises (ts->rejected_promise_list).

  • The function js_std_promise_rejection_check attempts to iterate over the rejected_promise_list to report unhandled rejections using a standard list loop.

  • The reason for a promise rejection is processed inside the loop, including calling js_std_dump_error1(ctx, rp->reason).

  • If the promise rejection reason is an Error object that defines a custom property getter (e.g., via Object.defineProperty), this getter is executed during the error dumping process.

  • The malicious custom getter can execute JavaScript code that calls catch() on the same rejected promise being processed.

  • Calling catch() internally triggers js_std_promise_rejection_tracker, which then removes and frees the current promise entry (JSRejectedPromiseEntry) from the rejected_promise_list.

  • Since the list iteration continues using the now-freed memory pointer (el), the subsequent loop access results in a Use-After-Free condition.

Record
EUVD-2025-34783
CVSS 4.0
8.8 HighCVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L
Updated
2026-11-02
GitHub AdvisoriesGHSA-3r39-xffq-r9cc 8.8

A Use-After-Free (UAF) vulnerability exists in the QuickJS engine's standard library when...

A Use-After-Free (UAF) vulnerability exists in the QuickJS engine's standard library when iterating over the global list of unhandled rejected promises (ts->rejected_promise_list).

  • The function js_std_promise_rejection_check attempts to iterate over the rejected_promise_list to report unhandled rejections using a standard list loop.

  • The reason for a promise rejection is processed inside the loop, including calling js_std_dump_error1(ctx, rp->reason).

  • If the promise rejection reason is an Error object that defines a custom property getter (e.g., via Object.defineProperty), this getter is executed during the error dumping process.

  • The malicious custom getter can execute JavaScript code that calls catch() on the same rejected promise being processed.

  • Calling catch() internally triggers js_std_promise_rejection_tracker, which then removes and frees the current promise entry (JSRejectedPromiseEntry) from the rejected_promise_list.

  • Since the list iteration continues using the now-freed memory pointer (el), the subsequent loop access results in a Use-After-Free condition.

Record
GHSA-3r39-xffq-r9cc
CVSS 4.0
8.8 HighCVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-416
Updated
2026-11-02
NVD 8.8

A Use-After-Free (UAF) vulnerability exists in the QuickJS engine's standard library when iterating over the global list of unhandled rejected promises (ts->rejected_promise_list).

  • The function js_std_promise_rejection_check attempts to iterate over the rejected_promise_list to report unhandled rejections using a standard list loop.

  • The reason for a promise rejection is processed inside the loop, including calling js_std_dump_error1(ctx, rp->reason).

  • If the promise rejection reason is an Error object that defines a custom property getter (e.g., via Object.defineProperty), this getter is executed during the error dumping process.

  • The malicious custom getter can execute JavaScript code that calls catch() on the same rejected promise being processed.

  • Calling catch() internally triggers js_std_promise_rejection_tracker, which then removes and frees the current promise entry (JSRejectedPromiseEntry) from the rejected_promise_list.

  • Since the list iteration continues using the now-freed memory pointer (el), the subsequent loop access results in a Use-After-Free condition.

Record
CVE-2025-62491
CVSS 4.0
8.8 HighCVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS 3.1
8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness
CWE-416
Updated
2026-11-02
OSV 8.8

A Use-After-Free (UAF) vulnerability exists in the QuickJS engine's standard library when iterating over the global list of unhandled rejected promises (ts->rejected_promise_list).

  • The function js_std_promise_rejection_check attempts to iterate over the rejected_promise_list to report unhandled rejections using a standard list loop.

  • The reason for a promise rejection is processed inside the loop, including calling js_std_dump_error1(ctx, rp->reason).

  • If the promise rejection reason is an Error object that defines a custom property getter (e.g., via Object.defineProperty), this getter is executed during the error dumping process.

  • The malicious custom getter can execute JavaScript code that calls catch() on the same rejected promise being processed.

  • Calling catch() internally triggers js_std_promise_rejection_tracker, which then removes and frees the current promise entry (JSRejectedPromiseEntry) from the rejected_promise_list.

  • Since the list iteration continues using the now-freed memory pointer (el), the subsequent loop access results in a Use-After-Free condition.

Record
CVE-2025-62491
CVSS 3.1
8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVDEBIAN-CVE-2025-62491 8.8

A Use-After-Free (UAF) vulnerability exists in the QuickJS engine's standard library when iterating over the global list of unhandled rejected promises (ts->rejected_promise_list). * The function js_std_promise_rejection_check attempts to iterate over the rejected_promise_list to report unhandled rejections using a standard list loop. * The reason for a promise rejection is processed inside the loop, including calling js_std_dump_error1(ctx, rp->reason). * If the promise rejection reason is an Error object that defines a custom property getter (e.g., via Object.defineProperty), this getter is executed during the error dumping process. * The malicious custom getter can execute JavaScript code that calls catch() on the same rejected promise being processed. * Calling catch() internally triggers js_std_promise_rejection_tracker, which then removes and frees the current promise entry (JSRejectedPromiseEntry) from the rejected_promise_list. * Since the list iteration continues using the now-freed memory pointer (el), the subsequent loop access results in a Use-After-Free condition.

Record
DEBIAN-CVE-2025-62491
CVSS 3.1
8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02
OSVUBUNTU-CVE-2025-62491 8.8

A Use-After-Free (UAF) vulnerability exists in the QuickJS engine's standard library when iterating over the global list of unhandled rejected promises (ts->rejected_promise_list). * The function js_std_promise_rejection_check attempts to iterate over the rejected_promise_list to report unhandled rejections using a standard list loop. * The reason for a promise rejection is processed inside the loop, including calling js_std_dump_error1(ctx, rp->reason). * If the promise rejection reason is an Error object that defines a custom property getter (e.g., via Object.defineProperty), this getter is executed during the error dumping process. * The malicious custom getter can execute JavaScript code that calls catch() on the same rejected promise being processed. * Calling catch() internally triggers js_std_promise_rejection_tracker, which then removes and frees the current promise entry (JSRejectedPromiseEntry) from the rejected_promise_list. * Since the list iteration continues using the now-freed memory pointer (el), the subsequent loop access results in a Use-After-Free condition.

Record
UBUNTU-CVE-2025-62491
CVSS 4.0
8.8 HighCVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L
CVSS 3.1
8.8 HighCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
quickjs
Debian:13
All versions, plus listed versions
2025.04.26-1
None known
quickjs
Debian:14
All versions, plus listed versions
2025.04.26-1
None known
quickjs
Ubuntu:Pro:24.04:LTS
All versions, plus listed versions
2021.03.27-12021.03.27-1ubuntu0.1~esm1
None known
quickjs
Ubuntu:25.10
All versions, plus listed versions
2024.01.13-52025.04.26-1
None known
quickjs
Ubuntu:26.10
All versions, plus listed versions
2025.04.26-1build1
None known
quickjs
Ubuntu:26.04:LTS
All versions, plus listed versions
2025.04.26-12025.04.26-1build1
None known

History

History
RecordedChangedSources
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2025-62491 is a high vulnerability (CVSS 8.8) in Quickjs, published October 16, 2025. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.41%, the 35th percentile. No source names a fixed version.

References

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