CVE-2025-39880 (GCVE-0-2025-39880)
Vulnerability from cvelistv5
Published
2025-09-23 06:00
Modified
2026-08-05 12:05
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: libceph: fix invalid accesses to ceph_connection_v1_info There is a place where generic code in messenger.c is reading and another place where it is writing to con->v1 union member without checking that the union member is active (i.e. msgr1 is in use). On 64-bit systems, con->v1.auth_retry overlaps with con->v2.out_iter, so such a read is almost guaranteed to return a bogus value instead of 0 when msgr2 is in use. This ends up being fairly benign because the side effect is just the invalidation of the authorizer and successive fetching of new tickets. con->v1.connect_seq overlaps with con->v2.conn_bufs and the fact that it's being written to can cause more serious consequences, but luckily it's not something that happens often.
References
Impacted products
Vendor Product Version
Linux Linux Version: cd1a677cad994021b19665ed476aea63f5d54f31
Version: cd1a677cad994021b19665ed476aea63f5d54f31
Version: cd1a677cad994021b19665ed476aea63f5d54f31
Version: cd1a677cad994021b19665ed476aea63f5d54f31
Version: cd1a677cad994021b19665ed476aea63f5d54f31
Version: cd1a677cad994021b19665ed476aea63f5d54f31
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              "value": "AV:N - The faulting/STANDBY transitions that reach both bad accesses are driven by the remote ceph peer\u0027s socket behaviour (connection reset, close, or a failed msgr2 handshake) over TCP, so a malicious or compromised MON/OSD/MDS \u2014 or an on-path attacker able to disrupt the session \u2014 triggers the code remotely. This matches how other libceph peer-data bugs (CVE-2026-22984, CVE-2026-22990) are scored.\nAC:L - No race or unusual precondition is needed: on any msgr2 connection the union misread is essentially deterministic (`v1.auth_retry` aliases a non-NULL pointer\u0027s low word), and the `connect_seq++` write happens on every fault-to-STANDBY followed by a queued message or keepalive, both of which the attacker can induce repeatedly by resetting the connection. msgr2 is the standard deployment mode for modern Ceph clusters, not a rare configuration.\nPR:N - The attacker needs no account or privilege on the victim host; it acts as the remote ceph peer or as a network attacker on the connection. The fault path is reachable during the msgr2 handshake before authentication completes, so it is a pre-authentication trigger.\nUI:N - Everything happens inside the libceph connection state machine and its workqueue handler on an already-established CephFS mount or mapped RBD device; no victim action is required at exploit time.\nS:U - The corruption is confined to kernel memory within the same security authority as the vulnerable code; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The confused `v1.auth_retry` read exposes the low 32 bits of a kernel heap pointer (into the connection object) to a branch decision and to the `dout()` log, and the corrupted `conn_bufs[]` pointer can direct handshake buffers \u2014 some of which, such as `authorizer_copy`, are copied out and sent to the peer \u2014 at unintended kernel memory, yielding attacker-visible disclosure.\nI:H - This is a union type confusion that performs out-of-bounds writes relative to the active member: zeroing half of `v2.out_iter`\u0027s iovec pointer and incrementing half of a `v2.conn_bufs[]` pointer, corrupting kernel pointer state. The maintainer explicitly notes the `connect_seq` write \"can cause more serious consequences,\" and the affected slot varies across the six affected stable branches because of differing struct layouts.\nA:H - A mangled `conn_bufs[]` entry is consumed by `kvfree()` in `free_conn_bufs()` and dereferenced as a handshake buffer, so the corruption can produce an invalid free or wild access resulting in an oops/panic, taking down a storage client node; the attacker can retrigger the condition indefinitely by repeatedly faulting the connection."
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          "url": "https://git.kernel.org/stable/c/591ea9c30737663a471b2bb07b27ddde86b020d5"
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