CVE-2026-43011: Linux kernel · net/x25: Fix potential double free of skb
Affects Linux kernelSource CVE Database V5
Not known to be exploited · CVSS 9.8 Critical · fixed in fa1dbc93530b34fab0da9862426fe9c918c74dc0 : patch Linux kernel as a priority.
Data as of 26 Oct 2026, 13:47 UTC
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 47% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers can reliably automate steps 1–4 of the kill chain
- Technical impact
- Total control over the software or total information disclosure
CISA SSVC assessment, 2026-10-16.
- Patch
- Available – fixed in fa1dbc93530b34fab0da9862426fe9c918c74dc0, f782dd382203b2a8c4552a628431b7de65a19a7b, d10a26aa4d072320530e6968ef945c8c575edf61 +5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
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: 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); }
References
- git.kernel.org/stable/c/5d0aa038a90b30c9bedde0c41c1fdcd98ecb16e9 (opens in a new tab)
- git.kernel.org/stable/c/3f5e3005984645bf5bd129c6b13149879580b1fb (opens in a new tab)
- git.kernel.org/stable/c/f782dd382203b2a8c4552a628431b7de65a19a7b (opens in a new tab)
- git.kernel.org/stable/c/143d4fa68ae9efb83b0c55b12cc7f0d03732a2b1 (opens in a new tab)
- git.kernel.org/stable/c/524371398d8463ea7e101fce2cbf3915645d1730 (opens in a new tab)
- git.kernel.org/stable/c/fa1dbc93530b34fab0da9862426fe9c918c74dc0 (opens in a new tab)
- git.kernel.org/stable/c/c87dd137c0dad07cc55f98181ff380b0c23d2878 (opens in a new tab)
- git.kernel.org/stable/c/d10a26aa4d072320530e6968ef945c8c575edf61 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-082556.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)