Linux: Use After Free
CVE-2026-23278 is a high-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an attacker with a low-privileged account, without any action from a user. The record lists versions ae8f3cedc5f5653a5bed45c5ed016fe156e2af55, c4d4e86fda707d89eaba80e343321737375f8582, 4830fb44d12f586f3f544609e086933649a9175a 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 0.22% 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 ae8f3cedc5f5653a5bed45c5ed016fe156e2af55 or c4d4e86fda707d89eaba80e343321737375f8582 or 4830fb44d12f586f3f544609e086933649a9175a or eb0948fa13298212c5f8b30ee48efdae4389ab09, whichever matches your release line, or a later version.
- Update Linux Kernel to 4.20 or 5.5 or 5.11 or 5.16, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 25aa2ad37c2162be1c0bc4fe6397f7e4c13f00f8 up to, but not including, ae8f3cedc5f5653a5bed45c5ed016fe156e2af55; d60be2da67d172aecf866302c91ea11533eca4d9 up to, but not including, c4d4e86fda707d89eaba80e343321737375f8582; 628bd3e49cba1c066228e23d71a852c23e26da73 up to, but not including, 4830fb44d12f586f3f544609e086933649a9175a; 628bd3e49cba1c066228e23d71a852c23e26da73 up to, but not including, eb0948fa13298212c5f8b30ee48efdae4389ab09; 628bd3e49cba1c066228e23d71a852c23e26da73 up to, but not including, de47a88c6b807910f05703fb6605f7efdaa11417; 628bd3e49cba1c066228e23d71a852c23e26da73 up to, but not including, 77c26b5056d693ffe5e9f040e946251cdb55ae55; 628bd3e49cba1c066228e23d71a852c23e26da73 up to, but not including, 7cb9a23d7ae40a702577d3d8bacb7026f04ac2a9; bc9f791d2593f17e39f87c6e2b3a36549a3705b1; and 10 more ranges | ae8f3cedc5f5653a5bed45c5ed016fe156e2af55, c4d4e86fda707d89eaba80e343321737375f8582, 4830fb44d12f586f3f544609e086933649a9175a, eb0948fa13298212c5f8b30ee48efdae4389ab09, de47a88c6b807910f05703fb6605f7efdaa11417, 77c26b5056d693ffe5e9f040e946251cdb55ae55 |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | all versions | Not stated |
| Linux | Linux Kernel | 4.19.316 up to, but not including, 4.20; 5.4.262 up to, but not including, 5.5; 5.10.188 up to, but not including, 5.11; 5.15.121 up to, but not including, 5.16; 6.1.36 up to, but not including, 6.2; 6.3.10 up to, but not including, 6.4; 6.4.1 up to, but not including, 6.12.78; 6.13 up to, but not including, 6.18.19; and 2 more ranges | 4.20, 5.5, 5.11, 5.16, 6.2, 6.4 |
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
- LocalThe attacker needs local access or must trick a user into running something.
- 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:L/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: netfilter: nf_tables: always walk all pending catchall elements During transaction processing we might have more than one catchall element: 1 live catchall element and 1 pending element that is coming as part of the new batch. If the map holding the catchall elements is also going away, its required to toggle all catchall elements and not just the first viable candidate. Otherwise, we get: WARNING: ./include/net/netfilter/nf_tables.h:1281 at nft_data_release+0xb7/0xe0 [nf_tables], CPU#2: nft/1404 RIP: 0010:nft_data_release+0xb7/0xe0 [nf_tables] [..] __nft_set_elem_destroy+0x106/0x380 [nf_tables] nf_tables_abort_release+0x348/0x8d0 [nf_tables] nf_tables_abort+0xcf2/0x3ac0 [nf_tables] nfnetlink_rcv_batch+0x9c9/0x20e0 [..]
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
Other references
Recent Use After Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 8.1 High severity
- 8.8 High severity
- 8.8 High severity
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