CyberSecBulletin
CVE-2026-43139NVD status: Modified

Linux: Use of Uninitialized Resource

Published Updated By the CyberSecBulletin desk

CVE-2026-43139 is a high-severity use of uninitialized resource vulnerability in Linux, with a CVSS 3.1 base score of 8.6 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 4f28141786e1fe884ce42a5197ba9beed540f0ea, 6535867673bf301d52aa00593a4d1d18cc3922fa, eb2ee15290af14c60b45cf2b73f5687d1d077d9b 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 0.38% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Linux to 4f28141786e1fe884ce42a5197ba9beed540f0ea or 6535867673bf301d52aa00593a4d1d18cc3922fa or eb2ee15290af14c60b45cf2b73f5687d1d077d9b or 719918fc88df6da023dfff370cd965151a5afd7f, whichever matches your release line, or a later version.
  2. Update Linux Kernel to 5.10.252 or 5.15.202 or 6.1.165 or 6.6.128, whichever matches your release line, or a later version.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LinuxLinuxa1e59abf824969554b90facd44a4ab16e265afa4 up to, but not including, 4f28141786e1fe884ce42a5197ba9beed540f0ea; a1e59abf824969554b90facd44a4ab16e265afa4 up to, but not including, 6535867673bf301d52aa00593a4d1d18cc3922fa; a1e59abf824969554b90facd44a4ab16e265afa4 up to, but not including, eb2ee15290af14c60b45cf2b73f5687d1d077d9b; a1e59abf824969554b90facd44a4ab16e265afa4 up to, but not including, 719918fc88df6da023dfff370cd965151a5afd7f; a1e59abf824969554b90facd44a4ab16e265afa4 up to, but not including, dc0abce055134cb83b0d981d31ceb20dda419787; a1e59abf824969554b90facd44a4ab16e265afa4 up to, but not including, c7221e7bd8fc2ef38a0b27be580d9d202281306b; a1e59abf824969554b90facd44a4ab16e265afa4 up to, but not including, 3dcd1664ac15eee6a690daec7c4ffc59190406f7; a1e59abf824969554b90facd44a4ab16e265afa4 up to, but not including, 1799d8abeabc68ec05679292aaf6cba93b343c05; and 1 more ranges4f28141786e1fe884ce42a5197ba9beed540f0ea, 6535867673bf301d52aa00593a4d1d18cc3922fa, eb2ee15290af14c60b45cf2b73f5687d1d077d9b, 719918fc88df6da023dfff370cd965151a5afd7f, dc0abce055134cb83b0d981d31ceb20dda419787, c7221e7bd8fc2ef38a0b27be580d9d202281306b
LinuxLinux Kernel2.6.19 up to, but not including, 5.10.252; 5.11 up to, but not including, 5.15.202; 5.16 up to, but not including, 6.1.165; 6.2 up to, but not including, 6.6.128; 6.7 up to, but not including, 6.12.75; 6.13 up to, but not including, 6.18.16; 6.19 up to, but not including, 6.19.6; 7.05.10.252, 5.15.202, 6.1.165, 6.6.128, 6.12.75, 6.18.16

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
LowSome restricted data can be read.
Integrity
LowLimited modification of data is possible.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H. Scored by CNA.

Official description

In the Linux kernel, the following vulnerability has been resolved: xfrm6: fix uninitialized saddr in xfrm6_get_saddr() xfrm6_get_saddr() does not check the return value of ipv6_dev_get_saddr(). When ipv6_dev_get_saddr() fails to find a suitable source address (returns -EADDRNOTAVAIL), saddr->in6 is left uninitialized, but xfrm6_get_saddr() still returns 0 (success). This causes the caller xfrm_tmpl_resolve_one() to use the uninitialized address in xfrm_state_find(), triggering KMSAN warning: ===================================================== BUG: KMSAN: uninit-value in xfrm_state_find+0x2424/0xa940 xfrm_state_find+0x2424/0xa940 xfrm_resolve_and_create_bundle+0x906/0x5a20 xfrm_lookup_with_ifid+0xcc0/0x3770 xfrm_lookup_route+0x63/0x2b0 ip_route_output_flow+0x1ce/0x270 udp_sendmsg+0x2ce1/0x3400 inet_sendmsg+0x1ef/0x2a0 __sock_sendmsg+0x278/0x3d0 __sys_sendto+0x593/0x720 __x64_sys_sendto+0x130/0x200 x64_sys_call+0x332b/0x3e70 do_syscall_64+0xd3/0xf80 entry_SYSCALL_64_after_hwframe+0x77/0x7f Local variable tmp.i.i created at: xfrm_resolve_and_create_bundle+0x3e3/0x5a20 xfrm_lookup_with_ifid+0xcc0/0x3770 ===================================================== Fix by checking the return value of ipv6_dev_get_saddr() and propagating the error.

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

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Use of Uninitialized Resource vulnerabilities

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