Answer in brief
CVE-2026-74577 records a Unknown severity vulnerability in net: mpls: initialize rtm_tos in mpls_getroute(). The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), 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.
A CVSS score is not reported in the current record. 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), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <95651461cf77cc6590fa08c87667717e5dcfa55d || >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <1fea5ff0eb4aa7e951bb3d380248566c473aa377 || >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <a5cdd2407dd890f741f59b8367e4c6c101cce154 || >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <2dc2fffc704a4365cae1aae078ba62223aaeff93 || >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <295dd295e2137e10e9a5b1891d97e0f08de76f03 | 95651461cf77cc6590fa08c87667717e5dcfa55d, 1fea5ff0eb4aa7e951bb3d380248566c473aa377, a5cdd2407dd890f741f59b8367e4c6c101cce154, 2dc2fffc704a4365cae1aae078ba62223aaeff93, 295dd295e2137e10e9a5b1891d97e0f08de76f03 |
| Linux/Linuxgeneric | 4.13 | Not reported |
| Linux/Linuxgeneric | >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <248718fd88b146d8bdc7610ecd1eb4cd16e0b5a1 || >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <466b474a8deb0c93b5280c6d261e5eda6482eca7 || >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <ba56f88aab18d982f2a21f11390f4d8a8897782a || >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <95651461cf77cc6590fa08c87667717e5dcfa55d || >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <1fea5ff0eb4aa7e951bb3d380248566c473aa377 || >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <a5cdd2407dd890f741f59b8367e4c6c101cce154 || >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <2dc2fffc704a4365cae1aae078ba62223aaeff93 || >=397fc9e5cefee0c33b86811fbddb0decb7288c52 <295dd295e2137e10e9a5b1891d97e0f08de76f03 | 248718fd88b146d8bdc7610ecd1eb4cd16e0b5a1, 466b474a8deb0c93b5280c6d261e5eda6482eca7, ba56f88aab18d982f2a21f11390f4d8a8897782a, 95651461cf77cc6590fa08c87667717e5dcfa55d, 1fea5ff0eb4aa7e951bb3d380248566c473aa377, a5cdd2407dd890f741f59b8367e4c6c101cce154, 2dc2fffc704a4365cae1aae078ba62223aaeff93, 295dd295e2137e10e9a5b1891d97e0f08de76f03 |
Published upstream
Aug 15, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Aug 15, 2026
In the Linux kernel, the following vulnerability has been resolved: net: mpls: initialize rtm_tos in mpls_getroute() mpls_getroute() builds the RTM_NEWROUTE reply to an RTM_GETROUTE request by filling a struct rtmsg allocated from an skb whose data area is not zeroed (alloc_skb(NLMSG_GOODSIZE, ...)). It sets every field of the header except rtm_tos: r = nlmsg_data(nlh); r->rtm_family = AF_MPLS; r->rtm_dst_len = 20; r->rtm_src_len = 0; r->rtm_table = RT_TABLE_MAIN; r->rtm_type = RTN_UNICAST; r->rtm_scope = RT_SCOPE_UNIVERSE; r->rtm_protocol = rt->rt_protocol; r->rtm_flags = 0; struct rtmsg has no padding, so the one uninitialised byte rtm_tos (offset 3) is copied straight to user space on recvmsg(), leaking a byte of uninitialised heap memory. This is in contrast to mpls_dump_route(), which fills the very same header and does set rtm_tos = 0. Initialize rtm_tos to 0, matching mpls_dump_route(). Reproduced with KMSAN by adding an MPLS route and issuing a non-RTM_F_FIB_MATCH RTM_GETROUTE for its label: BUG: KMSAN: kernel-infoleak in _copy_to_iter+0x36c/0x33f0 _copy_to_iter+0x36c/0x33f0 __skb_datagram_iter+0x196/0x12c0 skb_copy_datagram_iter+0x5b/0x210 netlink_recvmsg+0x37b/0xef0 ... Uninit was created at: __alloc_skb+0x8ca/0x10e0 mpls_getroute+0x1280/0x3a40 rtnetlink_rcv_msg+0x1138/0x15a0 ... Byte 19 of 64 is uninitialized (byte 19 = nlmsghdr(16) + rtmsg offset 3 = rtm_tos)
Quoted source text, attributed separately from HOL analysis.