Linux: Double Free
CVE-2026-45891 is a high-severity double 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 fb6a4c376d454b425555b1b0bda36e99f56ec307, 43015461662d41dcfb3bb95fadd8a2a42ad8eacf, 6dc10494cfe27b6f1e9adb7e293293ae39c50b7c 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 0.13% 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 fb6a4c376d454b425555b1b0bda36e99f56ec307 or 43015461662d41dcfb3bb95fadd8a2a42ad8eacf or 6dc10494cfe27b6f1e9adb7e293293ae39c50b7c or d2c785733dfb853ea0b53984c75662a1af230a94, whichever matches your release line, or a later version.
- Update Linux Kernel to 5.15.202 or 6.1.165 or 6.6.128 or 6.12.75, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 907676b130711fd1f627824559e92259db2061d1 up to, but not including, fb6a4c376d454b425555b1b0bda36e99f56ec307; 907676b130711fd1f627824559e92259db2061d1 up to, but not including, 43015461662d41dcfb3bb95fadd8a2a42ad8eacf; 907676b130711fd1f627824559e92259db2061d1 up to, but not including, 6dc10494cfe27b6f1e9adb7e293293ae39c50b7c; 907676b130711fd1f627824559e92259db2061d1 up to, but not including, d2c785733dfb853ea0b53984c75662a1af230a94; 907676b130711fd1f627824559e92259db2061d1 up to, but not including, fdbccddb7e7822016601829f95de4008e193f7bc; 907676b130711fd1f627824559e92259db2061d1 up to, but not including, c3659273860bed0c8e573b865e3769abc51225a8; 907676b130711fd1f627824559e92259db2061d1 up to, but not including, 6d2f142b1e4b203387a92519d9d2e34752a79dbb; 5.14 | fb6a4c376d454b425555b1b0bda36e99f56ec307, 43015461662d41dcfb3bb95fadd8a2a42ad8eacf, 6dc10494cfe27b6f1e9adb7e293293ae39c50b7c, d2c785733dfb853ea0b53984c75662a1af230a94, fdbccddb7e7822016601829f95de4008e193f7bc, c3659273860bed0c8e573b865e3769abc51225a8 |
| Linux | Linux Kernel | 5.14 up to, but not including, 5.15.202; 5.16 up to, but not including, 6.1.165; 6.2 up to, but not including, 6.6.128; 6.7 up to, but not including, 6.12.75; 6.13 up to, but not including, 6.18.14; 6.19 up to, but not including, 6.19.4 | 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.14, 6.19.4 |
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 NVD.
Official description
In the Linux kernel, the following vulnerability has been resolved: net: hns3: fix double free issue for tx spare buffer In hns3_set_ringparam(), a temporary copy (tmp_rings) of the ring structure is created for rollback. However, the tx_spare pointer in the original ring handle is incorrectly left pointing to the old backup memory. Later, if memory allocation fails in hns3_init_all_ring() during the setup, the error path attempts to free all newly allocated rings. Since tx_spare contains a stale (non-NULL) pointer from the backup, it is mistaken for a newly allocated buffer and is erroneously freed, leading to a double-free of the backup memory. The root cause is that the tx_spare field was not cleared after its value was saved in tmp_rings, leaving a dangling pointer. Fix this by setting tx_spare to NULL in the original ring structure when the creation of the new `tx_spare` fails. This ensures the error cleanup path only frees genuinely newly allocated buffers.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Double Free
The product calls free() twice on the same memory address.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- Ensure that each allocation is freed only once. After freeing a chunk, set the pointer to NULL to ensure the pointer cannot be freed again. In complicated error conditions, be sure that clean-up routines respect the state of allocation properly. If the language is object oriented, ensure that object destructors delete each chunk of memory only once.
- Use a static analysis tool to find double free instances.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/43015461662d41dcfb3bb95fadd8a2a42ad8eacf
- git.kernel.org/stable/c/6d2f142b1e4b203387a92519d9d2e34752a79dbb
- git.kernel.org/stable/c/6dc10494cfe27b6f1e9adb7e293293ae39c50b7c
- git.kernel.org/stable/c/c3659273860bed0c8e573b865e3769abc51225a8
- git.kernel.org/stable/c/d2c785733dfb853ea0b53984c75662a1af230a94
- git.kernel.org/stable/c/fb6a4c376d454b425555b1b0bda36e99f56ec307
- git.kernel.org/stable/c/fdbccddb7e7822016601829f95de4008e193f7bc
Recent Double Free vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 7.8 High severity
- 9.8 Critical severity
- 7.8 High severity
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