CVE-2025-62491
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.
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
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 High
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 - 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 High
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 - 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 High
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/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 High
CVSS: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 High
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/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 High
CVSS: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 High
CVSS: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 High
CVSS: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 High
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 - CVSS 3.1
- 8.8 High
CVSS: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
| Package | Affected | Fixed |
|---|---|---|
quickjsDebian:13 |
All versions, plus listed versions 2025.04.26-1 |
None known |
quickjsDebian:14 |
All versions, plus listed versions 2025.04.26-1 |
None known |
quickjsUbuntu:Pro:24.04:LTS |
All versions, plus listed versions 2021.03.27-12021.03.27-1ubuntu0.1~esm1 |
None known |
quickjsUbuntu:25.10 |
All versions, plus listed versions 2024.01.13-52025.04.26-1 |
None known |
quickjsUbuntu:26.10 |
All versions, plus listed versions 2025.04.26-1build1 |
None known |
quickjsUbuntu:26.04:LTS |
All versions, plus listed versions 2025.04.26-12025.04.26-1build1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE 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.