ipv4: igmp: Fix potential memory leaks in igmp_mod_timer() and igmp_stop_timer()
Key facts
- Attack vector
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- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
- —
- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 5 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: ipv4: igmp: Fix potential memory leaks in igmp_mod_timer() and igmp_stop_timer() When a timer is deleted and not re-armed in igmp_mod_timer(), or stopped in igmp_stop_timer(), the code currently decrements the reference counter of the multicast list entry @im using refcount_dec(&im->refcnt). However, both functions can be called from the RCU reader path: - igmp_mod_timer() via igmp_heard_query() -> for_each_pmc_rcu() - igmp_stop_timer() via igmp_rcv() -> igmp_heard_report() If the group im was concurrently removed from the list by ip_mc_dec_group(), its reference count might have already been decremented to 1. In this case, timer_delete() succeeds, and refcount_dec() decrements the refcount from 1 to 0. Since refcount_dec() does not free the object when it hits 0 (unlike ip_ma_put()), the im structure is leaked. Fix this by using ip_ma_put(im) instead of refcount_dec(&im->refcnt), and deferring the put until after the spinlock is released.
Why it matters now
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 6.1.191, 6.6.160, 6.12.114, 6.18.40, 7.1.5, 7.2
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-72321
- 2026-10-03 Alias added: GHSA-mrw5-54xq-r399
- 2026-10-21 Fix available: Linux/Linux@2d0effadf8d2cc9d006e4c4ab0ab6737aed28d77, Linux/Linux@40d6360ccf9bcbe17b5cb248a84e8e004aac2faa, Linux/[email protected] +1 · CNA
- 2026-10-21 2 new references · CNA
- 2026-10-30 Fix available: Linux/[email protected], Linux/Linux@d4fe30f4671033a27fba077b3976dc113ffc0169 · CNA
- 2026-10-30 1 new reference · CNA
References
Other 6
- https://git.kernel.org/stable/c/d4fe30f4671033a27fba077b3976dc113ffc0169
- https://git.kernel.org/stable/c/2d0effadf8d2cc9d006e4c4ab0ab6737aed28d77
- https://git.kernel.org/stable/c/40d6360ccf9bcbe17b5cb248a84e8e004aac2faa
- https://git.kernel.org/stable/c/f60ec3058a85447008b88b762c859d336163acb3
- https://git.kernel.org/stable/c/95128dc74425ec19ed4f2077ccc651e791ff4b75
- https://git.kernel.org/stable/c/3546deaa0c30a14c7cdb5dc8f2432cb428f0cd36
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Sources
- CVE-2026-72321 · CVE Program
- CVE-2026-72321 · NVD
- FIRST EPSS
- GHSA-mrw5-54xq-r399 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-72321 · Red Hat security data · CC BY 4.0
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