VulnerabilityPublished 11 Nov 2026

CVE-2026-123866: Use After Free

Source GCVE Database

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Authoritative record:CVE-2026-123866· High 7.5

Not known to be exploited · CVSS 7.5 High · fixed in 26.13.1 : patch node soon.

Data as of 11 Nov 2026, 22:35 UTC

CVSS 3.0 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CNA (openjs)	CVSS 3.0	7.5

Patch: Available – fixed in 26.13.1, 24.22.3, 22.23.5

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 11 Nov 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 11 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-52jx-xggf-7f6v

What to do

Upgrade node to 26.13.1, 24.22.3 or 22.23.5.

Affected software

Product	Affected	Fixed in
nodejsnode	Affected >=25.0.0 <26.13.1	Fixed in 26.13.1
nodejsnode	Affected >=23.0.0 <24.22.3	Fixed in 24.22.3
nodejsnode	Affected <22.23.5	Fixed in 22.23.5
npmnode`pkg:npm/node`Other threats	Affected <22.23.5 >=23.0.0 <24.22.3 >=25.0.0 <26.13.1	Fixed in 22.23.5 24.22.3 26.13.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, consider mitigating by limiting exposure to untrusted peers or disabling HTTP/2 if feasible.

Description

CVE-2026-123866 is a use-after-free vulnerability in Node.js HTTP/2 stream teardown that can leak response memory, including data from other connections' response buffers, to a peer. This occurs when a stream is torn down while a write is still backpressured, causing freed or unrelated heap memory to be sent instead of the intended response. The flaw affects Node.js versions 22.x, 24.x, and 26.x. The vulnerability has a high severity score of 7.5 and impacts confidentiality but not integrity or availability.

Impact

An attacker able to trigger stream teardown during backpressure can cause memory from freed response buffers, including contents from other connections, to be leaked to the attacker. This compromises confidentiality of response data across HTTP/2 connections. There is no impact on integrity or availability. The vulnerability has a CVSS 3.0 score of 7.5 (High) with network attack vector, low attack complexity, no privileges required, and no user interaction needed.

Summary

This vulnerability involves a use-after-free condition in the HTTP/2 stream teardown process in Node.js. When a stream is destroyed during backpressure on a write operation—triggered either by a remote peer's RST_STREAM frame or server-side per-stream timeout—the response buffer is freed prematurely while references to it remain. Consequently, memory that has been freed or unrelated heap memory may be written to the socket, leaking response data from other connections. The issue affects Node.js 22.x, 24.x, and 26.x branches. The vulnerability can be triggered remotely once certain window-size changes are present in versions 26.9.0 and 24.22.0, and also through application-initiated teardown such as idle timeouts on all supported lines.

CWE-416Use After Free (opens in a new tab)
Variant weaknessLikelihood of exploit: HighCWE Top 25 (2025): #7
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
Architecture and Design · Language Selection
Choose a language that provides automatic memory management.
Implementation · Attack Surface Reduction
When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2026, 22:35 UTC

WeaknessesCWE-416

Technical details

References

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