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CVE-2026-72323

ipv4: igmp: Fix potential UAF in igmp_gq_start_timer()

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.269, 5.15.220, 6.1.187, 6.6.145, 6.12.97, and 2 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: yes
  • Technical impact: total

Summary

In the Linux kernel, the following vulnerability has been resolved: ipv4: igmp: Fix potential UAF in igmp_gq_start_timer() A race condition exists between device teardown (inetdev_destroy) and incoming IGMP query processing (igmp_rcv), leading to a Use-After-Free in the IGMP timer callback. During device destruction, inetdev_destroy() drops the primary reference to in_device, which can drop its refcount to 0. The actual freeing of in_device memory is deferred via RCU (using call_rcu()). Concurrently, igmp_rcv() runs under RCU read lock and obtains the in_device pointer. Because the memory is RCU-protected, CPU-0 can safely dereference in_device even if its refcount has hit 0. However, if CPU-0 calls igmp_gq_start_timer() and re-arms the timer, it attempts to acquire a reference using in_dev_hold(). This increments the refcount from 0 to 1, triggering a "refcount_t: addition on 0" warning. Since the in_device memory is still scheduled to be freed after the RCU grace period (as the free callback does not check the refcount again), the device is freed while the timer is still armed. When the timer expires, it accesses the freed memory, causing a kernel panic. Fix this by using refcount_inc_not_zero() (via a new helper in_dev_hold_safe()) to prevent acquiring a reference if the device is already being destroyed. If the refcount is 0, we do not arm the timer. A similar issue in IPv6 MLD is fixed in a subsequent patch.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: yes · Technical impact: total

  3. Record last updated

Affected versions

  • Linux Linux

    From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 7265c747eec415ca3109a6a14a419f7ae433b780; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in d107b4c4f8274763b7ea5ab05d45cef78e4b81ba; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 74b301f7f197517016befb5f5dfab01f7bc64be5; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 40a1e998cb266ed4cb529a0bb4fee2b0ba732702; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 165258303357e54b75fc19b341ae2a2b7c9e3910; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 75e984fe0cb9e7fbde0c8ee838c61ce8573d3ea3; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 8d4394ffa40508e0de72f464af351f6ca6a6cdc3; From 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 · fixed in 7b19c0f81ed1fdaec6bc522569be367199a9edf3

  • Linux Linux

    2.6.12

  • KernelLinux

    From 2.6.12 · fixed in 5.10.269; From 5.11.0 · fixed in 5.15.220; From 5.16.0 · fixed in 6.1.187; From 6.2.0 · fixed in 6.6.145; From 6.7.0 · fixed in 6.12.97; From 6.13.0 · fixed in 6.18.40; From 6.19.0 · fixed in 7.1.5

References 8

git.kernel.org