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CVE-2026-43139

8.6 · HIGH

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().

Published May 6, 2026CWE-908EPSS 0.38%

Overview

CVE-2026-43139 is a high-severity vulnerability. It was published on May 6, 2026 and has a CVSS 3.1 base score of 8.6 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical 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_a

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refgit.kernel.org/stable/c/1799d8abeabc68ec05679292aaf6cba93b343c05Refgit.kernel.org/stable/c/3dcd1664ac15eee6a690daec7c4ffc59190406f7Refgit.kernel.org/stable/c/4f28141786e1fe884ce42a5197ba9beed540f0eaRefgit.kernel.org/stable/c/6535867673bf301d52aa00593a4d1d18cc3922faRefgit.kernel.org/stable/c/719918fc88df6da023dfff370cd965151a5afd7fRefgit.kernel.org/stable/c/c7221e7bd8fc2ef38a0b27be580d9d202281306bRefgit.kernel.org/stable/c/dc0abce055134cb83b0d981d31ceb20dda419787Refgit.kernel.org/stable/c/eb2ee15290af14c60b45cf2b73f5687d1d077d9b

How CyberStrike helps

Frequently asked questions

What is CVE-2026-43139?

CVE-2026-43139 is a high-severity vulnerability. It was published on May 6, 2026 and has a CVSS 3.1 base score of 8.6 (HIGH).

How severe is CVE-2026-43139?

This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-43139?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-43139?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-43139 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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