Raw vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HCVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.
Summary
CVE-2026-43011 is a critical-severity Double Free (CWE-415) vulnerability in Linux Linux Kernel. Its CVSS base score is 9.8 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 47th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SA-8 (Security and Privacy Engineering Principles) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-43011 is a vulnerability in the Linux kernel's X.25 networking implementation (net/x25) that results in a potential double free of a socket buffer (skb). The issue occurs when alloc_skb fails in x25_queue_rx_frame, which calls kfree_skb(skb) and returns 1 (error). This error propagates through x25_state3_machine (taking the else branch at line 278, setting queued=0) and x25_process_rx_frame, leading to x25_backlog_rcv calling kfree_skb(skb) again if queued=0.
The vulnerability carries a CVSS v3.1 base score of 9.8 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H), making it exploitable over the network (AV:N) by unauthenticated attackers (PR:N) with low attack complexity (AC:L) and no user interaction (UI:N). Exploitation via X.25 traffic could trigger the double free, enabling high-impact effects on confidentiality, integrity, and availability, such as kernel memory corruption or denial of service.
Patches addressing this issue are available in Linux kernel stable branches via the following commits: https://git.kernel.org/stable/c/143d4fa68ae9efb83b0c55b12cc7f0d03732a2b1, https://git.kernel.org/stable/c/3f5e3005984645bf5bd129c6b13149879580b1fb, https://git.kernel.org/stable/c/524371398d8463ea7e101fce2cbf3915645d1730, https://git.kernel.org/stable/c/5d0aa038a90b30c9bedde0c41c1fdcd98ecb16e9, and https://git.kernel.org/stable/c/c87dd137c0dad07cc55f98181ff380b0c23d2878. Affected systems should apply these updates, particularly if the X.25 module is in use.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-26610
Vulnerability Data
In the Linux kernel, the following vulnerability has been resolved: net/x25: Fix potential double free of skb When alloc_skb fails in x25_queue_rx_frame it calls kfree_skb(skb) at line 48 and returns 1 (error). This error propagates back through the call chain:…
more
x25_queue_rx_frame returns 1 | v x25_state3_machine receives the return value 1 and takes the else branch at line 278, setting queued=0 and returning 0 | v x25_process_rx_frame returns queued=0 | v x25_backlog_rcv at line 452 sees queued=0 and calls kfree_skb(skb) again This would free the same skb twice. Looking at x25_backlog_rcv: net/x25/x25_in.c:x25_backlog_rcv() { ... queued = x25_process_rx_frame(sk, skb); ... if (!queued) kfree_skb(skb); }
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 1 hardening rule · 1 OS baseline
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Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation explicitly includes dynamic analysis and fuzzing that locate double-free defects before release.
Security engineering principles can require memory-safe allocation patterns or language features that structurally eliminate double-free opportunities.
Flaw remediation processes require identification and correction of memory-management defects such as double free once discovered.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure SDLC practices directly prevent double-free errors via static analysis, safe memory APIs, and testing.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing in development can detect double-free conditions before release.
Secure coding standards directly address proper use of free() and similar functions.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (higher-evidence rows only; rows rated `none` are excluded).
Oracle Linux 8 (1 rule)
- V-248590 OL 8 must clear the page allocator to prevent use-after-free attacks. blocks CWE-415