Linux: Use After Free
CVE-2026-46323 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 3c6cc9f2ca65b6dd61b1af75452dc0e1cd0aad8d, 1f9c828556416fbe3f49386708ce999fc4d4da06, 479084ae0e1d9cb7929cb4298d35623de189f80a 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 0.14% 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 3c6cc9f2ca65b6dd61b1af75452dc0e1cd0aad8d or 1f9c828556416fbe3f49386708ce999fc4d4da06 or 479084ae0e1d9cb7929cb4298d35623de189f80a or e334cbf3388fd9334503a778a82d9e9f14dd2f71, whichever matches your release line, or a later version.
- Update Linux Kernel to 6.1.176 or 6.6.142 or 6.12.92 or 6.18.34, whichever matches your release line, or a later version.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Linux | Linux | 753f1ca4e1e50248a1b760c9774d6d6b354562cc up to, but not including, 3c6cc9f2ca65b6dd61b1af75452dc0e1cd0aad8d; 753f1ca4e1e50248a1b760c9774d6d6b354562cc up to, but not including, 1f9c828556416fbe3f49386708ce999fc4d4da06; 753f1ca4e1e50248a1b760c9774d6d6b354562cc up to, but not including, 479084ae0e1d9cb7929cb4298d35623de189f80a; 753f1ca4e1e50248a1b760c9774d6d6b354562cc up to, but not including, e334cbf3388fd9334503a778a82d9e9f14dd2f71; 753f1ca4e1e50248a1b760c9774d6d6b354562cc up to, but not including, 44bea2032af0425e4ce6d26a8af0ede79db49ec1; 753f1ca4e1e50248a1b760c9774d6d6b354562cc up to, but not including, 4db79a322db8c97f7b73b8a347395ef4d685eb40; 6.0 | 3c6cc9f2ca65b6dd61b1af75452dc0e1cd0aad8d, 1f9c828556416fbe3f49386708ce999fc4d4da06, 479084ae0e1d9cb7929cb4298d35623de189f80a, e334cbf3388fd9334503a778a82d9e9f14dd2f71, 44bea2032af0425e4ce6d26a8af0ede79db49ec1, 4db79a322db8c97f7b73b8a347395ef4d685eb40 |
| Red Hat | Red Hat Enterprise Linux 10 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 10.0 Extended Update Support | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 9.6 Extended Update Support | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift Container Platform 4.17 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift Container Platform 4.18 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift Container Platform 4.19 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift Container Platform 4.20 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift Container Platform 4.21 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 6 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 7 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux 8 | Not specified in the record | Not stated |
| Red Hat | Red Hat Enterprise Linux for NVIDIA 26 | Not specified in the record | Not stated |
| Red Hat | Red Hat OpenShift Container Platform 4 | Not specified in the record | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Siemens | SIMATIC S7-1500 TM MFP - GNU/Linux subsystem | all versions | Not stated |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) | V3.1.6 and later; V3.1.7 and later | Not stated |
| Linux | Linux Kernel | 6.0 up to, but not including, 6.1.176; 6.2 up to, but not including, 6.6.142; 6.7 up to, but not including, 6.12.92; 6.13 up to, but not including, 6.18.34; 6.19 up to, but not including, 7.0.11; 7.1 | 6.1.176, 6.6.142, 6.12.92, 6.18.34, 7.0.11 |
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.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CNA |
| CVSS 3.1 | 7.8 | High | CNA |
Official description
In the Linux kernel, the following vulnerability has been resolved: net: gro: don't merge zcopy skbs skb_gro_receive() can currently copy frags between the source and GRO skb, without checking the zerocopy status, and in particular the SKBFL_MANAGED_FRAG_REFS flag. When SKBFL_MANAGED_FRAG_REFS is set, the skb doesn't hold a reference on the pages in shinfo->frags. Appending those frags to another skb's frags without fixing up the page refcount can lead to UAF. When either the last skb in the GRO chain (the one we would append frags to) or the source skb is zerocopy, don't merge the skbs.
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
- git.kernel.org/stable/c/1f9c828556416fbe3f49386708ce999fc4d4da06
- git.kernel.org/stable/c/3c6cc9f2ca65b6dd61b1af75452dc0e1cd0aad8d
- git.kernel.org/stable/c/44bea2032af0425e4ce6d26a8af0ede79db49ec1
- git.kernel.org/stable/c/479084ae0e1d9cb7929cb4298d35623de189f80a
- git.kernel.org/stable/c/4db79a322db8c97f7b73b8a347395ef4d685eb40
- git.kernel.org/stable/c/e334cbf3388fd9334503a778a82d9e9f14dd2f71
Third-party and government advisories
- access.redhat.com/errata/RHSA-2026:27708Third Party Advisory
- access.redhat.com/errata/RHSA-2026:27731Third Party Advisory
- access.redhat.com/errata/RHSA-2026:27735Third Party Advisory
- access.redhat.com/errata/RHSA-2026:36018Third Party Advisory
- access.redhat.com/security/cve/CVE-2026-46323Third Party Advisory
- bugzilla.redhat.com/show_bug.cgi?id=2479832Third Party Advisory
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-46323.jsonThird Party Advisory
Other references
- access.redhat.com/errata/RHSA-2026:44230
- access.redhat.com/errata/RHSA-2026:44231
- access.redhat.com/errata/RHSA-2026:44259
- access.redhat.com/errata/RHSA-2026:44262
- access.redhat.com/errata/RHSA-2026:44270
- access.redhat.com/errata/RHSA-2026:47727
- access.redhat.com/errata/RHSA-2026:62639
- access.redhat.com/errata/RHSA-2026:62640
- access.redhat.com/errata/RHSA-2026:62641
- access.redhat.com/errata/RHSA-2026:62642
- cert-portal.siemens.com/productcert/html/ssa-019113.html
- cert-portal.siemens.com/productcert/html/ssa-457936.html
- cert-portal.siemens.com/productcert/html/ssa-784472.html
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