CVE-2025-38550 (GCVE-0-2025-38550)
Vulnerability from cvelistv5
Published
2025-08-16 11:34
Modified
2026-08-05 12:02
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ipv6: mcast: Delay put pmc->idev in mld_del_delrec() pmc->idev is still used in ip6_mc_clear_src(), so as mld_clear_delrec() does, the reference should be put after ip6_mc_clear_src() return.
References
Impacted products
Vendor Product Version
Linux Linux Version: b564ec4491d24b40900c64ab9e29a208f17f3108
Version: 63ed8de4be81b699ca727e9f8e3344bd487806d7
Version: 63ed8de4be81b699ca727e9f8e3344bd487806d7
Version: 63ed8de4be81b699ca727e9f8e3344bd487806d7
Version: 63ed8de4be81b699ca727e9f8e3344bd487806d7
Version: 63ed8de4be81b699ca727e9f8e3344bd487806d7
Version: 63ed8de4be81b699ca727e9f8e3344bd487806d7
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: mcast: Delay put pmc-\u003eidev in mld_del_delrec()\n\npmc-\u003eidev is still used in ip6_mc_clear_src(), so as mld_clear_delrec()\ndoes, the reference should be put after ip6_mc_clear_src() return."
        }
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
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              "lang": "en",
              "value": "AV:L - The vulnerable `mld_del_delrec()` path is entered from IPv6 multicast socket options (`IPV6_ADD_MEMBERSHIP`/`MCAST_JOIN_GROUP`) via `ipv6_sock_mc_join()` \u2192 `__ipv6_dev_mc_inc()`, which requires a local socket and local syscall access. The secondary `ipv6_mc_up()` call site is likewise local (RTNL/admin), so no remote packet processing reaches this code directly.\nAC:L - The attacker deterministically creates the required state himself \u2014 join a group, drop it (creating the `mc_tomb` entry through `mld_add_delrec()` in the default MLDv2 mode), then rejoin \u2014 with no race to win and no memory-layout precondition outside his control. All steps are ordinary `setsockopt()` calls that succeed on the first try.\nPR:L - Only an unprivileged local account is needed; `ipv6_sock_mc_join()`/`ipv6_sock_mc_drop()` perform no capability check, and joining a global-scope IPv6 multicast group is permitted to any user holding an `AF_INET6` socket. No `CAP_NET_ADMIN` or root is required, and the path is equally available inside an unprivileged user namespace with a veth/dummy device.\nUI:N - The entire sequence is driven by the attacker\u0027s own socket calls in a single process. No victim action, no filesystem mount, and no administrator involvement is needed.\nS:U - The premature reference drop and its consequences are confined to the kernel\u0027s own `inet6_dev` allocation and the network namespace that owns it. No hypervisor, IOMMU, or sandbox boundary is crossed, so the vulnerable component and impacted component share one security authority.\nC:H - Dropping the `inet6_dev` reference before `ip6_mc_clear_src()` finishes using `pmc-\u003eidev` is a use-after-free pattern on a refcounted network structure; once the object can be reclaimed, an attacker who sprays the freed `inet6_dev` slab gains a read primitive over attacker-shaped heap contents and adjacent kernel data. Per the UAF guidance this warrants High rather than a bounded pointer leak.\nI:H - A use-after-free on `inet6_dev` gives the attacker control over the contents subsequently dereferenced through `pmc-\u003eidev`, including the `mc_lock`/list pointers reached from `mc_dereference()`, which is the standard basis for heap-spray-driven arbitrary write and control-flow hijack. Type-confused reuse of the freed slab makes kernel memory modification achievable rather than merely theoretical.\nA:H - If the released reference is the last one, the following `ip6_mc_clear_src()` operates on freed memory, producing an oops or panic and taking the whole kernel down. The trigger is a repeatable unprivileged `setsockopt()` loop, so the crash can be induced at will."
            }
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        {
          "url": "https://git.kernel.org/stable/c/1b5b413094af8d88a31b5df3fd262f6baca53841"
        },
        {
          "url": "https://git.kernel.org/stable/c/6e4eec86fe5f6b3fdbc702d1d36ac2a6e7ec0806"
        },
        {
          "url": "https://git.kernel.org/stable/c/728db00a14cacb37f36e9382ab5fad55caf890cc"
        },
        {
          "url": "https://git.kernel.org/stable/c/dcbc346f50a009d8b7f4e330f9f2e22d6442fa26"
        },
        {
          "url": "https://git.kernel.org/stable/c/7929d27c747eafe8fca3eecd74a334503ee4c839"
        },
        {
          "url": "https://git.kernel.org/stable/c/5f18e0130194550dff734e155029ae734378b5ea"
        },
        {
          "url": "https://git.kernel.org/stable/c/ae3264a25a4635531264728859dbe9c659fad554"
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      "title": "ipv6: mcast: Delay put pmc-\u003eidev in mld_del_delrec()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-38550",
    "datePublished": "2025-08-16T11:34:18.619Z",
    "dateReserved": "2025-04-16T04:51:24.024Z",
    "dateUpdated": "2026-08-05T12:02:49.916Z",
    "state": "PUBLISHED"
  },
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