CyberSecBulletin
CVE-2026-23395NVD status: Modified

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix…

Published Updated By the CyberSecBulletin desk

CVE-2026-23395 is a high-severity improper input validation vulnerability in Linux, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited from the same local network by an unauthenticated attacker, without any action from a user. The record lists versions 10a7a702542240d5edb2b39450ac951c59ccd009, 46e5b71666fb7652082e4e214a3365f4b14f1dc3, fb4a3a26483f3ea2cd21c7a2f7c45d5670600465 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 0.26% 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 10a7a702542240d5edb2b39450ac951c59ccd009 or 46e5b71666fb7652082e4e214a3365f4b14f1dc3 or fb4a3a26483f3ea2cd21c7a2f7c45d5670600465 or 2124d82fd25e1671bb3ceb37998af5aae5903e06, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.253 or 5.15.203 or 6.1.167 or 6.6.130, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 10a7a702542240d5edb2b39450ac951c59ccd009; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 46e5b71666fb7652082e4e214a3365f4b14f1dc3; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, fb4a3a26483f3ea2cd21c7a2f7c45d5670600465; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 2124d82fd25e1671bb3ceb37998af5aae5903e06; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 6b949a6b33cbdf621d9fc6f0c48ac00915dbf514; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 8d0d94f8ba5b3a0beec3b0da558b9bea48018117; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, e72ee455297b794b852e5cea8d2d7bb17312172a; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 5b3e2052334f2ff6d5200e952f4aa66994d09899; and 1 more ranges10a7a702542240d5edb2b39450ac951c59ccd009, 46e5b71666fb7652082e4e214a3365f4b14f1dc3, fb4a3a26483f3ea2cd21c7a2f7c45d5670600465, 2124d82fd25e1671bb3ceb37998af5aae5903e06, 6b949a6b33cbdf621d9fc6f0c48ac00915dbf514, 8d0d94f8ba5b3a0beec3b0da558b9bea48018117
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versionsNot stated
LinuxLinux Kernel5.7.1 up to, but not including, 5.10.253; 5.11 up to, but not including, 5.15.203; 5.16 up to, but not including, 6.1.167; 6.2 up to, but not including, 6.6.130; 6.7 up to, but not including, 6.12.78; 6.13 up to, but not including, 6.18.20; 6.19 up to, but not including, 6.19.10; 5.7; and 1 more ranges5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20

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
AdjacentThe attacker must be on the same local network segment.
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
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

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

Scoring systemScoreSeverityScored by
CVSS 3.18.8HighCNA
CVSS 3.18.8HighNVD

Official description

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix accepting multiple L2CAP_ECRED_CONN_REQ Currently the code attempts to accept requests regardless of the command identifier which may cause multiple requests to be marked as pending (FLAG_DEFER_SETUP) which can cause more than L2CAP_ECRED_MAX_CID(5) to be allocated in l2cap_ecred_rsp_defer causing an overflow. The spec is quite clear that the same identifier shall not be used on subsequent requests: 'Within each signaling channel a different Identifier shall be used for each successive request or indication.' https://www.bluetooth.com/wp-content/uploads/Files/Specification/HTML/Core-62/out/en/host/logical-link-control-and-adaptation-protocol-specification.html#UUID-32a25a06-4aa4-c6c7-77c5-dcfe3682355d So this attempts to check if there are any channels pending with the same identifier and rejects if any are found.

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

The underlying weakness: Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How developers prevent this class of flaw

  • Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses.
  • Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
  • Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.

More Improper Input Validation vulnerabilities (CWE-20)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Improper Input Validation vulnerabilities

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