Linux: Use After Free
CVE-2026-63919 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 remotely over the network by an attacker with a low-privileged account, without any action from a user. The record lists versions 7ee59eda8820b758ed29e1cd3222359c7b97302c, 2df7059a18afb7d3aee6c36cad5d371c198111d4, 8dfabcba6a943a7a02ebe1e1637c361ba96acbaa 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 0.65% chance of exploitation within 30 days, higher than 52% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Update Linux to 7ee59eda8820b758ed29e1cd3222359c7b97302c or 2df7059a18afb7d3aee6c36cad5d371c198111d4 or 8dfabcba6a943a7a02ebe1e1637c361ba96acbaa or 48ce101cd630d6745b6923b5bad8358bc4c119da, 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 | 7b3801927e52f8621de311277f7fc727635019e7 up to, but not including, 7ee59eda8820b758ed29e1cd3222359c7b97302c; 7b3801927e52f8621de311277f7fc727635019e7 up to, but not including, 2df7059a18afb7d3aee6c36cad5d371c198111d4; 7b3801927e52f8621de311277f7fc727635019e7 up to, but not including, 8dfabcba6a943a7a02ebe1e1637c361ba96acbaa; 7b3801927e52f8621de311277f7fc727635019e7 up to, but not including, 48ce101cd630d6745b6923b5bad8358bc4c119da; 7b3801927e52f8621de311277f7fc727635019e7 up to, but not including, 55ddfc41451f01c588089cd74957a05311b6f202; 7b3801927e52f8621de311277f7fc727635019e7 up to, but not including, 9f7ebb45a83afc3216e855e57d51bb4bc9b5232e; 7b3801927e52f8621de311277f7fc727635019e7 up to, but not including, 9f67a36e91bb50d358760f381f233913fe5c09f8; 7b3801927e52f8621de311277f7fc727635019e7 up to, but not including, c16f74dc1d75d0e2e7670076d5375deda110ebeb; and 1 more ranges | 7ee59eda8820b758ed29e1cd3222359c7b97302c, 2df7059a18afb7d3aee6c36cad5d371c198111d4, 8dfabcba6a943a7a02ebe1e1637c361ba96acbaa, 48ce101cd630d6745b6923b5bad8358bc4c119da, 55ddfc41451f01c588089cd74957a05311b6f202, 9f7ebb45a83afc3216e855e57d51bb4bc9b5232e |
| Linux | Linux Kernel | 5.6 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
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- 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:N/AC:L/PR:L/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: xfrm: input: hold netns during deferred transport reinjection Transport-mode reinjection stores a struct net pointer in skb->cb and uses it later from xfrm_trans_reinject(). That pointer must stay valid until the deferred callback runs. Take a netns reference when queueing deferred reinjection work and drop it after the callback completes. Use maybe_get_net() so the queueing path does not revive a namespace that is already being torn down. This keeps the existing workqueue design and fixes the netns lifetime handling in one place for all users of xfrm_trans_queue_net().
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/2df7059a18afb7d3aee6c36cad5d371c198111d4
- git.kernel.org/stable/c/48ce101cd630d6745b6923b5bad8358bc4c119da
- git.kernel.org/stable/c/55ddfc41451f01c588089cd74957a05311b6f202
- git.kernel.org/stable/c/7ee59eda8820b758ed29e1cd3222359c7b97302c
- git.kernel.org/stable/c/8dfabcba6a943a7a02ebe1e1637c361ba96acbaa
- git.kernel.org/stable/c/9f67a36e91bb50d358760f381f233913fe5c09f8
- git.kernel.org/stable/c/9f7ebb45a83afc3216e855e57d51bb4bc9b5232e
- git.kernel.org/stable/c/c16f74dc1d75d0e2e7670076d5375deda110ebeb
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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