Linux: Use After Free
CVE-2026-53247 is a critical-severity use after free vulnerability in Linux, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 72775977e89c25c99ee84d2c5baa3f86a8ba5cb4, 459c6f35c58cf0fd5247e55d73ddaa29571d9b7e, e634408d2b0cd939cfe019398a21fb47b7a8ffe3 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 0.69% chance of exploitation within 30 days, higher than 53% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to 72775977e89c25c99ee84d2c5baa3f86a8ba5cb4 or 459c6f35c58cf0fd5247e55d73ddaa29571d9b7e or e634408d2b0cd939cfe019398a21fb47b7a8ffe3 or 2d86aeb46d5f69c704065a8c69822582787272a1, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.6.143 or 6.12.94 or 6.18.36 or 7.0.13, whichever matches your release line, or a later version.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 2d7605a729062bb554f03c5983d8cfb8c0b42e9c up to, but not including, 72775977e89c25c99ee84d2c5baa3f86a8ba5cb4; 2d7605a729062bb554f03c5983d8cfb8c0b42e9c up to, but not including, 459c6f35c58cf0fd5247e55d73ddaa29571d9b7e; 2d7605a729062bb554f03c5983d8cfb8c0b42e9c up to, but not including, e634408d2b0cd939cfe019398a21fb47b7a8ffe3; 2d7605a729062bb554f03c5983d8cfb8c0b42e9c up to, but not including, 2d86aeb46d5f69c704065a8c69822582787272a1; 2d7605a729062bb554f03c5983d8cfb8c0b42e9c up to, but not including, 80df409e1a483676826a6c66e693dba6ac507751; 6.2 | 72775977e89c25c99ee84d2c5baa3f86a8ba5cb4, 459c6f35c58cf0fd5247e55d73ddaa29571d9b7e, e634408d2b0cd939cfe019398a21fb47b7a8ffe3, 2d86aeb46d5f69c704065a8c69822582787272a1, 80df409e1a483676826a6c66e693dba6ac507751 |
| Linux | Linux Kernel | 6.2 up to, but not including, 6.6.143; 6.7 up to, but not including, 6.12.94; 6.13 up to, but not including, 6.18.36; 6.19 up to, but not including, 7.0.13; 7.1 | 6.6.143, 6.12.94, 6.18.36, 7.0.13 |
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
- 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:N/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: net: ethernet: mtk_eth_soc: Fix use-after-free in metadata dst teardown mtk_free_dev() calls metadata_dst_free() which frees the metadata_dst with kfree() immediately, bypassing the RCU grace period. In the RX path, skb_dst_set_noref() sets a non-refcounted pointer from the skb to the metadata_dst. This function requires RCU read-side protection and the dst must remain valid until all RCU readers complete. Since metadata_dst_free() calls kfree() directly, a use-after-free can occur if any skb still holds a noref pointer to the dst when the driver tears it down. Replace metadata_dst_free() with dst_release() which properly goes through the refcount path: when the refcount drops to zero, it schedules the actual free via call_rcu_hurry(), ensuring all RCU readers have completed before the memory is freed.
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.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
- git.kernel.org/stable/c/2d86aeb46d5f69c704065a8c69822582787272a1
- git.kernel.org/stable/c/459c6f35c58cf0fd5247e55d73ddaa29571d9b7e
- git.kernel.org/stable/c/72775977e89c25c99ee84d2c5baa3f86a8ba5cb4
- git.kernel.org/stable/c/80df409e1a483676826a6c66e693dba6ac507751
- git.kernel.org/stable/c/e634408d2b0cd939cfe019398a21fb47b7a8ffe3
Recent Use After Free vulnerabilities
- 7.5 High severity
- 9.8 Critical severity
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
- 8.2 High severity
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