Unknown

CVE-2026-74577 — 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)

Published Aug 15, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Linux

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+1

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.17%

ahead of 6% of scored CVEs · Oct 28, 2026

Affects

Linux

CVSS base

—

Score not published yet.

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Linux Linux).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes, errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	≥ 397fc9e5cefee0c33b86811fbddb0decb7288c52 and < 248718fd88b146d8bdc7610ecd1eb4cd16e0b5a1≥ 397fc9e5cefee0c33b86811fbddb0decb7288c52 and < 466b474a8deb0c93b5280c6d261e5eda6482eca7≥ 397fc9e5cefee0c33b86811fbddb0decb7288c52 and < ba56f88aab18d982f2a21f11390f4d8a8897782a≥ 397fc9e5cefee0c33b86811fbddb0decb7288c52 and < 95651461cf77cc6590fa08c87667717e5dcfa55d≥ 397fc9e5cefee0c33b86811fbddb0decb7288c52 and < 1fea5ff0eb4aa7e951bb3d380248566c473aa377≥ 397fc9e5cefee0c33b86811fbddb0decb7288c52 and < a5cdd2407dd890f741f59b8367e4c6c101cce154≥ 397fc9e5cefee0c33b86811fbddb0decb7288c52 and < 2dc2fffc704a4365cae1aae078ba62223aaeff93≥ 397fc9e5cefee0c33b86811fbddb0decb7288c52 and < 295dd295e2137e10e9a5b1891d97e0f08de76f03 and 1 more version 4.13	Vulnerable	CVE Program (cve.org) e CISA ADP

EPSS over time FIRST

Oct 15, 2026 → Oct 28, 2026 · 13 reading(s) · max 0.17%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Not enough vector or weakness data: use the affected application’s logs as a starting point.

application logs

Timeline

What happened to this CVE, newest first.

2026
Record published
Oct 15, 2026
Affected products added · linux/linux
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Source status changed · → Received
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Aug 15, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

8 on the record

git.kernel.org/stable/c/2dc2fffc704a4365cae1aae078ba62223aaeff93
NIST National Vulnerability Database
git.kernel.org/stable/c/95651461cf77cc6590fa08c87667717e5dcfa55d
NIST National Vulnerability Database
git.kernel.org/stable/c/a5cdd2407dd890f741f59b8367e4c6c101cce154
NIST National Vulnerability Database
git.kernel.org/stable/c/295dd295e2137e10e9a5b1891d97e0f08de76f03
NIST National Vulnerability Database
git.kernel.org/stable/c/ba56f88aab18d982f2a21f11390f4d8a8897782a
NIST National Vulnerability Database
git.kernel.org/stable/c/1fea5ff0eb4aa7e951bb3d380248566c473aa377
NIST National Vulnerability Database
git.kernel.org/stable/c/466b474a8deb0c93b5280c6d261e5eda6482eca7
NIST National Vulnerability Database
git.kernel.org/stable/c/248718fd88b146d8bdc7610ecd1eb4cd16e0b5a1
NIST National Vulnerability Database

Elsewhere on this site

Linux
every CVE for this vendor

Related CVEs (same products)

Unknown CVE-2026-99216 Drivers: hv: Don't reset VMBus connection state on error/exit paths 1d
Unknown CVE-2026-99215 power: supply: core: prevent unregistering a power supply while a callback runs 1d
Unknown CVE-2026-99207 scsi: target: Disable interrupts while holding delayed_cmd_lock 1d
Unknown CVE-2026-99208 drm/xe/oa: Zero OA buffer at allocation 1d
Unknown CVE-2026-99209 drm/xe: skip eviction of a BO with no resource 1d
Unknown CVE-2026-99210 accel/rocket: clear rdev on device init failure 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No CVSS score published by NVD, the CNA, CISA or GitHub so far.
No fixed version, patch or mitigation documented.
No CISA SSVC assessment.
No CWE classification.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-74577 is "net: mpls: initialize rtm_tos in mpls_getroute()", rated Unknown. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. EPSS 0.17% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.