Linux: Use of Uninitialized Resource
CVE-2026-63857 is a critical-severity use of uninitialized resource 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 dba5f4959653e4c212beb746594952e8645d1115, f670fa4b19ceddc6d215dda4997888ccba9bbc61, d78c8ab7bd84952e053d0c622b7fc1b4ad8a19a3 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 0.39% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Linux to dba5f4959653e4c212beb746594952e8645d1115 or f670fa4b19ceddc6d215dda4997888ccba9bbc61 or d78c8ab7bd84952e053d0c622b7fc1b4ad8a19a3 or bde34e84edc8b5571fbde7e941e175a4293ee1eb, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.12.114 or 6.18.33 or 7.0.10, 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 | 23020f04932701d5c8363e60756f12b43b8ed752 up to, but not including, dba5f4959653e4c212beb746594952e8645d1115; 23020f04932701d5c8363e60756f12b43b8ed752 up to, but not including, f670fa4b19ceddc6d215dda4997888ccba9bbc61; 23020f04932701d5c8363e60756f12b43b8ed752 up to, but not including, d78c8ab7bd84952e053d0c622b7fc1b4ad8a19a3; 23020f04932701d5c8363e60756f12b43b8ed752 up to, but not including, bde34e84edc8b5571fbde7e941e175a4293ee1eb; 6.11 | dba5f4959653e4c212beb746594952e8645d1115, f670fa4b19ceddc6d215dda4997888ccba9bbc61, d78c8ab7bd84952e053d0c622b7fc1b4ad8a19a3, bde34e84edc8b5571fbde7e941e175a4293ee1eb |
| Linux | Linux Kernel | 6.11 up to, but not including, 6.12.114; 6.13 up to, but not including, 6.18.33; 6.19 up to, but not including, 7.0.10; 7.1 | 6.12.114, 6.18.33, 7.0.10 |
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: airoha: Do not read uninitialized fragment address in airoha_dev_xmit() The transmit loop in airoha_dev_xmit() reads fragment address and length during its final iteration, when the loop index equals skb_shinfo(skb)->nr_frags, at which point the fragment data is uninitialized. While these values are never consumed, the read itself is unsafe and may trigger a page fault. Fix this by avoiding the fragment read on the last iteration. Additionally, move the skb pointer from the first to the last used packet descriptor, so that airoha_qdma_tx_napi_poll() defers freeing the skb until the final descriptor is processed.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use of Uninitialized Resource
The product uses or accesses a resource that has not been initialized.
How developers prevent this class of flaw
- Explicitly initialize the resource before use. If this is performed through an API function or standard procedure, follow all required steps.
- Pay close attention to complex conditionals that affect initialization, since some branches might not perform the initialization.
- Avoid race conditions (CWE-362) during initialization routines.
More Use of Uninitialized Resource vulnerabilities (CWE-908)
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Recent Use of Uninitialized Resource vulnerabilities
- 7.8 High severity
- 7.8 High severity
- 8.2 High severity
- 9.1 Critical severity
- 8.8 High severity
- 9.8 Critical severity
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