CVE-2026-74630: Linux Vulnerability

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: prevent in6_dev_get() from resurrecting inet6_dev in6_dev_get() reads dev->ip6_ptr under RCU and then unconditionally increments its refcount. Device teardown can clear the pointer and drop the last reference between these operations. The increment then resurrects an object whose RCU free has already been queued, so callers can use it after it is freed. Use refcount_inc_not_zero() and return NULL when the object has already reached zero. RCU keeps the memory accessible through the attempted reference acquisition, and a successful increment pins the object for the caller. An independent run on the exact unpatched 6f5156d7a31a (v7.2-rc3) kernel reproduced the invalid reference acquisition as UID 1000: refcount_t: addition on 0; use-after-free. ip6_mc_source+0xef4/0x17e0 It was followed by the corresponding reference underflow in ip6_mc_source(). The supplied trace from the same unpatched revision additionally shows the access after the RCU read-side section ends: BUG: KASAN: slab-use-after-free in mutex_lock+0x76/0xe0 Write of size 8 at addr ffff888015b50240 by task poc/1219 Bug found and triaged by OpenAI Security Research and validated by Trail of Bits.

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Linux	Linux	>= 8814c4b533817df825485ff32ce6ac406c3a54d1, < 785d908f8d21c8bc78b6fb2c2932ab662bf6918a; >= 8814c4b533817df825485ff32ce6ac406c3a54d1, < aedcfefdb5b7ed7f8a6196a3e68a25bdbe51d2f8; >= 8814c4b533817df825485ff32ce6ac406c3a54d1, < 145812b678de9f3b59780173be3c0d22ed60dd93; >= 8814c4b533817df825485ff32ce6ac406c3a54d1, < cc5bd568f9b7683e60841b6fd02c10d64535bd6e; >= 8814c4b533817df825485ff32ce6ac406c3a54d1, < 1c206d461c680c3151daa3c89fc26eaf5bf98a7f; >= 8814c4b533817df825485ff32ce6ac406c3a54d1, < 680fbd7942185448eadb990a3d10a53eb946b702; >= 8814c4b533817df825485ff32ce6ac406c3a54d1, < 14e812ab41df0cac033479da835ec9a5de633404; >= 8814c4b533817df825485ff32ce6ac406c3a54d1, < 0e243671bc7b8eaf00f83dd2f4367436dc0cff98
Linux	Linux	2.6.19

References

Timeline

Published: Aug 22, 2026
Last Modified: Aug 22, 2026
Status: Received

Frequently Asked Questions

What is CVE-2026-74630?

In the Linux kernel, the following vulnerability has been resolved: ipv6: prevent in6_dev_get() from resurrecting inet6_dev in6_dev_get() reads dev->ip6_ptr under RCU and then unconditionally increments its refcount. Device teardown can clear the pointer and drop the last reference between these operations. The increment then resurrects an object whose RCU free has already been queued, so callers can use it after it is freed. Use refcount_inc_not_zero() and return NULL when the object has already reached zero. RCU keeps the memory accessible through the attempted reference acquisition, and a successful increment pins the object for the caller. An independent run on the exact unpatched 6f5156d7a31a (v7.2-rc3) kernel reproduced the invalid reference acquisition as UID 1000: refcount_t: addition on 0; use-after-free. ip6_mc_source+0xef4/0x17e0 It was followed by the corresponding reference underflow in ip6_mc_source(). The supplied trace from the same unpatched revision additionally shows the access after the RCU read-side section ends: BUG: KASAN: slab-use-after-free in mutex_lock+0x76/0xe0 Write of size 8 at addr ffff888015b50240 by task poc/1219 Bug found and triaged by OpenAI Security Research and validated by Trail of Bits.

How severe is CVE-2026-74630?

Severity scoring for CVE-2026-74630 is pending analysis.

How do I fix CVE-2026-74630?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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