Linux: Use After Free
CVE-2026-63975 is a high-severity use after free 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 3c8eaa91eb433c450426539290be4ffe282e9f00, ecfed1e0d8efecad6737a0d83e21d2fd021d8c48, e6833e737a51db1e5ea0401322acf5e22abd8be6 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 0.27% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 3c8eaa91eb433c450426539290be4ffe282e9f00 or ecfed1e0d8efecad6737a0d83e21d2fd021d8c48 or e6833e737a51db1e5ea0401322acf5e22abd8be6 or 6319b38fe69f56ed95680ade485b957a53fff642, whichever matches your release line, or a later version.
- 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
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 3c8eaa91eb433c450426539290be4ffe282e9f00; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, ecfed1e0d8efecad6737a0d83e21d2fd021d8c48; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, e6833e737a51db1e5ea0401322acf5e22abd8be6; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 6319b38fe69f56ed95680ade485b957a53fff642; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 291eec1041c918c460dc9702e44edd17794b4a4b; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 41e29548b5e8b5e5fcf708786b3bea67cab107fa; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, d153b8898c0051eb8b6a083b35cbe304a5886bd5; 15f02b91056253e8cdc592888f431da0731337b8 up to, but not including, 41c2713b204e6cb6a94587bc6bf6935107df5479; and 1 more ranges | 3c8eaa91eb433c450426539290be4ffe282e9f00, ecfed1e0d8efecad6737a0d83e21d2fd021d8c48, e6833e737a51db1e5ea0401322acf5e22abd8be6, 6319b38fe69f56ed95680ade485b957a53fff642, 291eec1041c918c460dc9702e44edd17794b4a4b, 41e29548b5e8b5e5fcf708786b3bea67cab107fa |
| Linux | Linux Kernel | 5.7 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; 7.1 | 5.10.259, 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
- 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: Bluetooth: L2CAP: Fix possible crash on l2cap_ecred_conn_rsp If dcid is received for an already-assigned destination CID the spec requires that both channels to be discarded, but calling l2cap_chan_del may invalidate the tmp cursor created by list_for_each_entry_safe and in fact it is the wrong procedure as the chan->dcid may be assigned previously it really needs to be disconnected. Calling l2cap_chan_clone directly may still lead to l2cap_chan_del so instead schedule l2cap_chan_timeout with delay 0 to close the channel asynchronously.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
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.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- 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.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/291eec1041c918c460dc9702e44edd17794b4a4b
- git.kernel.org/stable/c/3c8eaa91eb433c450426539290be4ffe282e9f00
- git.kernel.org/stable/c/41c2713b204e6cb6a94587bc6bf6935107df5479
- git.kernel.org/stable/c/41e29548b5e8b5e5fcf708786b3bea67cab107fa
- git.kernel.org/stable/c/6319b38fe69f56ed95680ade485b957a53fff642
- git.kernel.org/stable/c/d153b8898c0051eb8b6a083b35cbe304a5886bd5
- git.kernel.org/stable/c/e6833e737a51db1e5ea0401322acf5e22abd8be6
- git.kernel.org/stable/c/ecfed1e0d8efecad6737a0d83e21d2fd021d8c48
Recent Use After Free vulnerabilities
- 8.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
- 7.8 High severity
- 9.8 Critical severity
- 8.8 High severity
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