Answer in brief
CVE-2026-31707 records a High severity (CVSS 7.1) vulnerability in ksmbd: validate response sizes in ipc_validate_msg(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 7.1. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=0626e6641f6b467447c81dd7678a69c66f7746cf <52518503a1a00bc33e9522c4eb05df023e3ae978 || >=0626e6641f6b467447c81dd7678a69c66f7746cf <bf396208418371174869baba9434535cd3288e80 || >=0626e6641f6b467447c81dd7678a69c66f7746cf <7dd0c858e1909769a4c91842724315ee74f1a5f1 || >=0626e6641f6b467447c81dd7678a69c66f7746cf <299db777ea0cfa5c407e41b045c24a14c034c27b || >=0626e6641f6b467447c81dd7678a69c66f7746cf <99c631d0366c1eab8fb188fe66425f4581ebdde4 || >=0626e6641f6b467447c81dd7678a69c66f7746cf <d6a6aa81eac2c9bff66dc6e191179cb69a14426b | 52518503a1a00bc33e9522c4eb05df023e3ae978, bf396208418371174869baba9434535cd3288e80, 7dd0c858e1909769a4c91842724315ee74f1a5f1, 299db777ea0cfa5c407e41b045c24a14c034c27b, 99c631d0366c1eab8fb188fe66425f4581ebdde4, d6a6aa81eac2c9bff66dc6e191179cb69a14426b |
| Linux/Linuxgeneric | 5.15 | Not reported |
Published upstream
May 1, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 30, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 30, 2026
In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate response sizes in ipc_validate_msg() ipc_validate_msg() computes the expected message size for each response type by adding (or multiplying) attacker-controlled fields from the daemon response to a fixed struct size in unsigned int arithmetic. Three cases can overflow: KSMBD_EVENT_RPC_REQUEST: msg_sz = sizeof(struct ksmbd_rpc_command) + resp->payload_sz; KSMBD_EVENT_SHARE_CONFIG_REQUEST: msg_sz = sizeof(struct ksmbd_share_config_response) + resp->payload_sz; KSMBD_EVENT_LOGIN_REQUEST_EXT: msg_sz = sizeof(struct ksmbd_login_response_ext) + resp->ngroups * sizeof(gid_t); resp->payload_sz is __u32 and resp->ngroups is __s32. Each addition can wrap in unsigned int; the multiplication by sizeof(gid_t) mixes signed and size_t, so a negative ngroups is converted to SIZE_MAX before the multiply. A wrapped value of msg_sz that happens to equal entry->msg_sz bypasses the size check on the next line, and downstream consumers (smb2pdu.c:6742 memcpy using rpc_resp->payload_sz, kmemdup in ksmbd_alloc_user using resp_ext->ngroups) then trust the unverified length. Use check_add_overflow() on the RPC_REQUEST and SHARE_CONFIG_REQUEST paths to detect integer overflow without constraining functional payload size; userspace ksmbd-tools grows NDR responses in 4096-byte chunks for calls like NetShareEnumAll, so a hard transport cap is unworkable on the response side. For LOGIN_REQUEST_EXT, reject resp->ngroups outside the signed [0, NGROUPS_MAX] range up front and report the error from ipc_validate_msg() so it fires at the IPC boundary; with that bound the subsequent multiplication and addition stay well below UINT_MAX. The now-redundant ngroups check and pr_err in ksmbd_alloc_user() are removed. This is the response-side analogue of aab98e2dbd64 ("ksmbd: fix integer overflows on 32 bit systems"), which hardened the request side.
Quoted source text, attributed separately from HOL analysis.