Linux: Double Free
CVE-2026-64580 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 97e032e5733e49471fb73de117ea2ac1ac7c479a, df6856c2dda9187601d29b5fbd7a81b3b178cedf, 43de8a49335e611adb271bbd52e84dfbc11fc185 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 97e032e5733e49471fb73de117ea2ac1ac7c479a or df6856c2dda9187601d29b5fbd7a81b3b178cedf or 43de8a49335e611adb271bbd52e84dfbc11fc185 or ff636d7b7cba6dea82ecf580415ea57f2c1a11b6, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 84c4a9dfbf430861e7588d95ae3ff61535dca351 up to, but not including, 97e032e5733e49471fb73de117ea2ac1ac7c479a; 84c4a9dfbf430861e7588d95ae3ff61535dca351 up to, but not including, df6856c2dda9187601d29b5fbd7a81b3b178cedf; 84c4a9dfbf430861e7588d95ae3ff61535dca351 up to, but not including, 43de8a49335e611adb271bbd52e84dfbc11fc185; 84c4a9dfbf430861e7588d95ae3ff61535dca351 up to, but not including, ff636d7b7cba6dea82ecf580415ea57f2c1a11b6; 84c4a9dfbf430861e7588d95ae3ff61535dca351 up to, but not including, e078da1b4e11390cff3201c19a9a1fe70c5b934f; 84c4a9dfbf430861e7588d95ae3ff61535dca351 up to, but not including, 136992de9bb91871084ae52d172610541c76e4d2; a7e22d0c0e81dde129a51ee413644124f4b59954; 01b0d887f67a388fb2a658ee2bdd74e5ba146818; and 7 more ranges | 97e032e5733e49471fb73de117ea2ac1ac7c479a, df6856c2dda9187601d29b5fbd7a81b3b178cedf, 43de8a49335e611adb271bbd52e84dfbc11fc185, ff636d7b7cba6dea82ecf580415ea57f2c1a11b6, e078da1b4e11390cff3201c19a9a1fe70c5b934f, 136992de9bb91871084ae52d172610541c76e4d2 |
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: xfrm6: clear dst.dev on error to avoid double netdev_put in xfrm6_fill_dst() On the error path where in6_dev_get(dev) returns NULL, xfrm6_fill_dst() releases the device reference with netdev_put() but leaves xdst->u.dst.dev set. dst_destroy() later calls netdev_put(dst->dev) again, so the same net_device reference is released twice, underflowing its refcount (ref_tracker WARNING + "unregister_netdevice: waiting for <dev> to become free"). Clear xdst->u.dst.dev after the netdev_put(), the same way the XFRM device-offload paths xfrm_dev_state_add() and xfrm_dev_policy_add() in net/xfrm/xfrm_device.c NULL ->dev when releasing the reference on error. ref_tracker: reference already released. ref_tracker: allocated in: xfrm6_fill_dst (net/ipv6/xfrm6_policy.c:86) ... udpv6_sendmsg (net/ipv6/udp.c:1696) ... ref_tracker: freed in: xfrm6_fill_dst (net/ipv6/xfrm6_policy.c:90) ... WARNING: lib/ref_tracker.c:322 at ref_tracker_free+0x58b/0x780 dst_destroy (net/core/dst.c:115) rcu_core handle_softirqs ...
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: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
- git.kernel.org/stable/c/136992de9bb91871084ae52d172610541c76e4d2
- git.kernel.org/stable/c/43de8a49335e611adb271bbd52e84dfbc11fc185
- git.kernel.org/stable/c/97e032e5733e49471fb73de117ea2ac1ac7c479a
- git.kernel.org/stable/c/df6856c2dda9187601d29b5fbd7a81b3b178cedf
- git.kernel.org/stable/c/e078da1b4e11390cff3201c19a9a1fe70c5b934f
- git.kernel.org/stable/c/ff636d7b7cba6dea82ecf580415ea57f2c1a11b6
Recent Double Free vulnerabilities
- 7.8 High severity
- 8.7 High severity
- 9.8 Critical severity
- 7.8 High severity
- 9.8 Critical severity
- 9.8 Critical severity
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