CyberSecBulletin
CVE-2026-31622NVD status: Modified

Linux: Buffer Copy without Checking Size of Input

Published Updated By the CyberSecBulletin desk

CVE-2026-31622 is a high-severity buffer copy without checking size of input 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 9ba6bb09e00b922d902f684f575779e5433fe6e3, f83b399aa05a0712e3b1569a30d3d90b3533d2ef, 20663102c14566e900e1d2f679e30b7f1694f387 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 0.29% 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 9ba6bb09e00b922d902f684f575779e5433fe6e3 or f83b399aa05a0712e3b1569a30d3d90b3533d2ef or 20663102c14566e900e1d2f679e30b7f1694f387 or 2819f34e08bdffb6f06a51c67948ec5737fb166a, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 6.6.136 or 6.12.83 or 6.18.24 or 6.19.14, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinux2c66daecc4092e6049673c281b2e6f0d5e59a94c up to, but not including, 9ba6bb09e00b922d902f684f575779e5433fe6e3; 2c66daecc4092e6049673c281b2e6f0d5e59a94c up to, but not including, f83b399aa05a0712e3b1569a30d3d90b3533d2ef; 2c66daecc4092e6049673c281b2e6f0d5e59a94c up to, but not including, 20663102c14566e900e1d2f679e30b7f1694f387; 2c66daecc4092e6049673c281b2e6f0d5e59a94c up to, but not including, 2819f34e08bdffb6f06a51c67948ec5737fb166a; 2c66daecc4092e6049673c281b2e6f0d5e59a94c up to, but not including, 1bec5698b55aa2be5c3b983dba657c01d0fd3dbc; 2c66daecc4092e6049673c281b2e6f0d5e59a94c up to, but not including, 5a59bf70c38ee1eb4be03bab830bbc3a6f0bd1f1; 2c66daecc4092e6049673c281b2e6f0d5e59a94c up to, but not including, 8d9d9bf3565271ca7ab9c716a94e87296177e7ba; 2c66daecc4092e6049673c281b2e6f0d5e59a94c up to, but not including, cc024a3de265ef6c58957f4990eccb9f806208cb; and 2 more ranges9ba6bb09e00b922d902f684f575779e5433fe6e3, f83b399aa05a0712e3b1569a30d3d90b3533d2ef, 20663102c14566e900e1d2f679e30b7f1694f387, 2819f34e08bdffb6f06a51c67948ec5737fb166a, 1bec5698b55aa2be5c3b983dba657c01d0fd3dbc, 5a59bf70c38ee1eb4be03bab830bbc3a6f0bd1f1
SiemensSIMATIC S7-1500 TM MFP - GNU/Linux subsystemall versionsNot stated
LinuxLinux Kernel3.13 up to, but not including, 6.6.136; 6.7 up to, but not including, 6.12.83; 6.13 up to, but not including, 6.18.24; 6.19 up to, but not including, 6.19.14; 7.0 up to, but not including, 7.0.16.6.136, 6.12.83, 6.18.24, 6.19.14, 7.0.1

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 CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: NFC: digital: Bounds check NFC-A cascade depth in SDD response handler The NFC-A anti-collision cascade in digital_in_recv_sdd_res() appends 3 or 4 bytes to target->nfcid1 on each round, but the number of cascade rounds is controlled entirely by the peer device. The peer sets the cascade tag in the SDD_RES (deciding 3 vs 4 bytes) and the cascade-incomplete bit in the SEL_RES (deciding whether another round follows). ISO 14443-3 limits NFC-A to three cascade levels and target->nfcid1 is sized accordingly (NFC_NFCID1_MAXSIZE = 10), but nothing in the driver actually enforces this. This means a malicious peer can keep the cascade running, writing past the heap-allocated nfc_target with each round. Fix this by rejecting the response when the accumulated UID would exceed the buffer. Commit e329e71013c9 ("NFC: nci: Bounds check struct nfc_target arrays") fixed similar missing checks against the same field on the NCI path.

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

The underlying weakness: Buffer Copy without Checking Size of Input

The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.

How developers prevent this class of flaw

  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
  • Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.

More Buffer Copy without Checking Size of Input vulnerabilities (CWE-120)

Timeline

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

References

Recent Buffer Copy without Checking Size of Input vulnerabilities

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