CyberSecBulletin
CVE-2026-31711NVD status: Modified

Linux: Missing Release of Memory after Effective Lifetime

Published Updated By the CyberSecBulletin desk

CVE-2026-31711 is a high-severity missing release of memory after effective lifetime vulnerability in Linux, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions dc2e7d595d68cf1be1ba64e3d30ebf3266bf7242, 60734c8bc3b4aa0672e251f08dda81977e4b5387, 97f8d2648ef4871e4cd335e2d769cb40054a6772 as the first without the flaw, so updating Linux to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.55% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to dc2e7d595d68cf1be1ba64e3d30ebf3266bf7242 or 60734c8bc3b4aa0672e251f08dda81977e4b5387 or 97f8d2648ef4871e4cd335e2d769cb40054a6772 or 295a9fc6789d1011c36ded9f0f2907bb34fa0de4, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.16 or 6.2 or 6.6.136 or 6.12.84, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux4210c3555db4b38bade92331b153e583261f05f9 up to, but not including, dc2e7d595d68cf1be1ba64e3d30ebf3266bf7242; d5d7847e57ac69fa99c18b363a34419bcdb5a281 up to, but not including, 60734c8bc3b4aa0672e251f08dda81977e4b5387; 0d0d4680db22eda1eea785c47bbf66a9b33a8b16 up to, but not including, 97f8d2648ef4871e4cd335e2d769cb40054a6772; 0d0d4680db22eda1eea785c47bbf66a9b33a8b16 up to, but not including, 295a9fc6789d1011c36ded9f0f2907bb34fa0de4; 0d0d4680db22eda1eea785c47bbf66a9b33a8b16 up to, but not including, 283027aa93380380a0994f35dde3ec95318f2654; 0d0d4680db22eda1eea785c47bbf66a9b33a8b16 up to, but not including, fb48185bcd946d42de7017cf27f912f8ab26acf0; 0d0d4680db22eda1eea785c47bbf66a9b33a8b16 up to, but not including, 6551300dc452ac16a855a83dbd1e74899542d3b3; 5.15.91 up to, but not including, 5.15.210; and 2 more rangesdc2e7d595d68cf1be1ba64e3d30ebf3266bf7242, 60734c8bc3b4aa0672e251f08dda81977e4b5387, 97f8d2648ef4871e4cd335e2d769cb40054a6772, 295a9fc6789d1011c36ded9f0f2907bb34fa0de4, 283027aa93380380a0994f35dde3ec95318f2654, fb48185bcd946d42de7017cf27f912f8ab26acf0
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versionsNot stated
LinuxLinux Kernel5.15.91 up to, but not including, 5.16; 6.1.9 up to, but not including, 6.2; 6.2.1 up to, but not including, 6.6.136; 6.7 up to, but not including, 6.12.84; 6.13 up to, but not including, 6.18.25; 6.19 up to, but not including, 7.0.2; 6.25.16, 6.2, 6.6.136, 6.12.84, 6.18.25, 7.0.2

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: smb: server: fix active_num_conn leak on transport allocation failure Commit 77ffbcac4e56 ("smb: server: fix leak of active_num_conn in ksmbd_tcp_new_connection()") addressed the kthread_run() failure path. The earlier alloc_transport() == NULL path in the same function has the same leak, is reachable pre-authentication via any TCP connect to port 445, and was empirically reproduced on UML (ARCH=um, v7.0-rc7): a small number of forced allocation failures were sufficient to put ksmbd into a state where every subsequent connection attempt was rejected for the remainder of the boot. ksmbd_kthread_fn() increments active_num_conn before calling ksmbd_tcp_new_connection() and discards the return value, so when alloc_transport() returns NULL the socket is released and -ENOMEM returned without decrementing the counter. Each such failure permanently consumes one slot from the max_connections pool; once cumulative failures reach the cap, atomic_inc_return() hits the threshold on every subsequent accept and every new connection is rejected. The counter is only reset by module reload. An unauthenticated remote attacker can drive the server toward the memory pressure that makes alloc_transport() fail by holding open connections with large RFC1002 lengths up to MAX_STREAM_PROT_LEN (0x00FFFFFF); natural transient allocation failures on a loaded host produce the same drift more slowly. Mirror the existing rollback pattern in ksmbd_kthread_fn(): on the alloc_transport() failure path, decrement active_num_conn gated on server_conf.max_connections. Repro details: with the patch reverted, forced alloc_transport() NULL returns leaked counter slots and subsequent connection attempts -- including legitimate connects issued after the forced-fail window had closed -- were all rejected with "Limit the maximum number of connections". With this patch applied, the same connect sequence produces no rejections and the counter cycles cleanly between zero and one on every accept.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Missing Release of Memory after Effective Lifetime

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

How developers prevent this class of flaw

  • Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone. For example, glibc in Linux provides protection against free of invalid pointers. When using Xcode to target OS X or iOS, enable automatic reference counting (ARC). To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std
  • Use an abstraction library to abstract away risky APIs. Not a complete solution.
  • Consider using the Boehm-Demers-Weiser garbage collector (bdwgc), which can help avoid leaks.

More Missing Release of Memory after Effective Lifetime vulnerabilities (CWE-401)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Recent Missing Release of Memory after Effective Lifetime vulnerabilities

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