What’s Vulnerable › Vulnerabilities

CVE-2026-43139: xfrm6: fix uninitialized saddr in xfrm6_get_saddr()

• Severity: high (CVSS 8.6 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-06 · updated 2026-10-19
• Weakness: CWE-908

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.

Affected products

• Linux kernel: from 2.6.19 before 5.10.252; from 5.11 before 5.15.202; from 5.16 before 6.1.165; from 6.2 before 6.6.128; from 6.7 before 6.12.75; from 6.13 before 6.18.16 — fixed in 5.10.252, 5.15.202, 6.1.165, 6.12.75, 6.18.16, 6.19.6

How to fix

Upgrade to a fixed version: Linux kernel 5.10.252, 5.15.202, 6.1.165, 6.12.75. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/1799d8abeabc68ec05679292aaf6cba93b343c05
• https://git.kernel.org/stable/c/3dcd1664ac15eee6a690daec7c4ffc59190406f7
• https://git.kernel.org/stable/c/4f28141786e1fe884ce42a5197ba9beed540f0ea
• https://git.kernel.org/stable/c/6535867673bf301d52aa00593a4d1d18cc3922fa
• https://git.kernel.org/stable/c/719918fc88df6da023dfff370cd965151a5afd7f
• https://git.kernel.org/stable/c/c7221e7bd8fc2ef38a0b27be580d9d202281306b
• https://git.kernel.org/stable/c/dc0abce055134cb83b0d981d31ceb20dda419787
• https://git.kernel.org/stable/c/eb2ee15290af14c60b45cf2b73f5687d1d077d9b

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