CyberSecBulletin
CVE-2026-63893NVD status: Analyzed

Linux: Integer Overflow or Wraparound

Published Updated By the CyberSecBulletin desk

CVE-2026-63893 is a high-severity integer overflow or wraparound vulnerability in Linux, with a CVSS 3.1 base score of 8.1 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 6a63623621639acbb39bc2d9fb09559681716695, e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36, 9fee50c4e1e42f6d3cbe30df584f9f648f626071 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 0.39% 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 6a63623621639acbb39bc2d9fb09559681716695 or e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36 or 9fee50c4e1e42f6d3cbe30df584f9f648f626071 or 8d4a758b407ab3de3be86d1ceadfa35d717d30c7, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.259 or 5.15.210 or 6.1.176 or 6.6.143, whichever matches your release line, or a later version.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxcdae7c07e3e3509eaabc18c1640a55dc5b99c179 up to, but not including, 6a63623621639acbb39bc2d9fb09559681716695; cdae7c07e3e3509eaabc18c1640a55dc5b99c179 up to, but not including, e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36; cdae7c07e3e3509eaabc18c1640a55dc5b99c179 up to, but not including, 9fee50c4e1e42f6d3cbe30df584f9f648f626071; cdae7c07e3e3509eaabc18c1640a55dc5b99c179 up to, but not including, 8d4a758b407ab3de3be86d1ceadfa35d717d30c7; cdae7c07e3e3509eaabc18c1640a55dc5b99c179 up to, but not including, 5c06a3043ad944f087bb2ae0aae28d820bb9f460; cdae7c07e3e3509eaabc18c1640a55dc5b99c179 up to, but not including, 31b98e503ecca8077e5247253dd5425ab84bc96d; cdae7c07e3e3509eaabc18c1640a55dc5b99c179 up to, but not including, a47784aee77f33f786dc5d7375db821bdae68792; cdae7c07e3e3509eaabc18c1640a55dc5b99c179 up to, but not including, 01deda0152066c6c955f0619114ea6afa070aaec; and 1 more ranges6a63623621639acbb39bc2d9fb09559681716695, e8a0b0a93a6ef958e70b1dd4930beb6dc0026b36, 9fee50c4e1e42f6d3cbe30df584f9f648f626071, 8d4a758b407ab3de3be86d1ceadfa35d717d30c7, 5c06a3043ad944f087bb2ae0aae28d820bb9f460, 31b98e503ecca8077e5247253dd5425ab84bc96d
LinuxLinux Kernel4.15 up to, but not including, 5.10.259; 5.11 up to, but not including, 5.15.210; 5.16 up to, but not including, 6.1.176; 6.2 up to, but not including, 6.6.143; 6.7 up to, but not including, 6.12.93; 6.13 up to, but not including, 6.18.35; 6.19 up to, but not including, 7.0.12; 7.15.10.259, 5.15.210, 6.1.176, 6.6.143, 6.12.93, 6.18.35

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
NoneNothing can be modified.
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:N/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: thunderbolt: property: Reject u32 wrap in tb_property_entry_valid() entry->value is u32 and entry->length is u16; the sum is performed in u32 and wraps. A malicious XDomain peer can pick value = 0xffffff00, length = 0x100 so the sum 0x100000000 wraps to 0 and passes the > block_len check. tb_property_parse() then passes entry->value to parse_dwdata() as a dword offset into the property block, reading attacker-directed memory far past the allocation. For TEXT-typed entries with the "deviceid" or "vendorid" keys this lands in xd->device_name / xd->vendor_name and is readable back via the per-XDomain device_name / vendor_name sysfs attributes; the leak is NUL-bounded (kstrdup() stops at the first zero byte) and untargeted (the attacker picks a delta, not an absolute address). DATA-typed entries are parsed into property->value.data but not generically surfaced to userspace. Use check_add_overflow() so a wrapped sum is rejected.

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

The underlying weakness: Integer Overflow or Wraparound

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.

How developers prevent this class of flaw

  • Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
  • Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. If possible, choose a language or compiler that performs automatic bounds checking.
  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Use libraries or frameworks that make it easier to handle numbers without unexpected consequences. Examples include safe integer handling packages such as SafeInt (C++) or IntegerLib (C or C++).

More Integer Overflow or Wraparound vulnerabilities (CWE-190)

Timeline

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

References

Recent Integer Overflow or Wraparound vulnerabilities

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