net: mpls: initialize rtm_tos in mpls_getroute()
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)
CVE-2026-74577
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: osv:CVE-2026-74577
Kernel
Source reference: /affected/1/package/name
- Affected versions
- Not stated in this record
- Fixed versions
- 5.10.265
Source reference:
/affected/1/ranges5.15.216Source reference:
/affected/1/ranges6.1.183Source reference:
/affected/1/ranges6.6.151Source reference:
/affected/1/ranges6.12.103Source reference:
/affected/1/ranges6.18.44Source reference:
/affected/1/ranges7.1.8Source reference:
/affected/1/ranges - Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"ranges": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"type": "GIT",
"events": [
{
"introduced": "397fc9e5cefee0c33b86811fbddb0decb7288c52"
},
{
"fixed": "248718fd88b146d8bdc7610ecd1eb4cd16e0b5a1"
},
{
"fixed": "466b474a8deb0c93b5280c6d261e5eda6482eca7"
},
{
"fixed": "ba56f88aab18d982f2a21f11390f4d8a8897782a"
},
{
"fixed": "95651461cf77cc6590fa08c87667717e5dcfa55d"
},
{
"fixed": "1fea5ff0eb4aa7e951bb3d380248566c473aa377"
},
{
"fixed": "a5cdd2407dd890f741f59b8367e4c6c101cce154"
},
{
"fixed": "2dc2fffc704a4365cae1aae078ba62223aaeff93"
},
{
"fixed": "295dd295e2137e10e9a5b1891d97e0f08de76f03"
}
]
}
],
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74577.json"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "4.13.0"
},
{
"fixed": "5.10.265"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "5.11.0"
},
{
"fixed": "5.15.216"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "5.16.0"
},
{
"fixed": "6.1.183"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "6.2.0"
},
{
"fixed": "6.6.151"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "6.7.0"
},
{
"fixed": "6.12.103"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "6.13.0"
},
{
"fixed": "6.18.44"
}
]
},
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "6.19.0"
},
{
"fixed": "7.1.8"
}
]
}
],
"package": {
"name": "Kernel",
"ecosystem": "Linux"
},
"database_specific": {
"source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74577.json"
}
}
]- Related CVEs
- CVE-2026-74577
Source reference:
/id
Publisher severity
No explicit severity was provided.
- Event
- #50769 · Revision 1
- Added to Heist Feed
- Publisher date