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NVD / CVE Program· CNA Linux

CVE-2026-74577: net: mpls: initialize rtm_tos in mpls_getroute()

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.16% (FIRST EPSS).
  • Fixed version: Linux Linux 1fea5ff0eb4aa7e951bb3d380248566c473aa377, 248718fd88b146d8bdc7610ecd1eb4cd16e0b5a1, 295dd295e2137e10e9a5b1891d97e0f08de76f03; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.152.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 1fea5ff0eb4aa7e951bb3d380248566c473aa377, 248718fd88b146d8bdc7610ecd1eb4cd16e0b5a1, 295dd295e2137e10e9a5b1891d97e0f08de76f03; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.152.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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)

—No exploit Fix available
Published
Aug 15, 2026
Updated
Nov 6, 2026
EPSS
0.1% · 5th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

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  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 4.13affected
    • 397fc9e5cefee0c33b86811fbddb0decb7288c52 and later · before 248718fd88b146d8bdc7610ecd1eb4cd16e0b5a1affected · git
    • 397fc9e5cefee0c33b86811fbddb0decb7288c52 and later · before 466b474a8deb0c93b5280c6d261e5eda6482eca7affected · git
    • 397fc9e5cefee0c33b86811fbddb0decb7288c52 and later · before ba56f88aab18d982f2a21f11390f4d8a8897782aaffected · git
    • 397fc9e5cefee0c33b86811fbddb0decb7288c52 and later · before 95651461cf77cc6590fa08c87667717e5dcfa55daffected · git
    • 397fc9e5cefee0c33b86811fbddb0decb7288c52 and later · before 1fea5ff0eb4aa7e951bb3d380248566c473aa377affected · git
    • 397fc9e5cefee0c33b86811fbddb0decb7288c52 and later · before a5cdd2407dd890f741f59b8367e4c6c101cce154affected · git
    • 397fc9e5cefee0c33b86811fbddb0decb7288c52 and later · before 2dc2fffc704a4365cae1aae078ba62223aaeff93affected · git
    • 397fc9e5cefee0c33b86811fbddb0decb7288c52 and later · before 295dd295e2137e10e9a5b1891d97e0f08de76f03affected · git
    • before 4.13not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.187-16.1.187-1
Debian:12linux-6.12before 6.12.107-1~deb12u16.12.107-1~deb12u1
Debian:13linuxbefore 6.12.105-16.12.105-1
Debian:14linuxbefore 7.1.8-17.1.8-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-74575Aug 15, 2026 · thunderbolt: Prevent XDomain delayed work use-after-free on disconnect
    35Monitor
  • ← EarlierCVE-2026-74576Aug 15, 2026 · mm/slab: prevent unbounded recursion in free path with new kmalloc type
    30Monitor
  • Later →CVE-2026-74578Aug 16, 2026 · crypto: algif_skcipher - force synchronous processing on trees without ctx->state
    28Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux1fea5ff0eb4aa7e951bb3d380248566c473aa377Vendor (CNA)
Linux Linux248718fd88b146d8bdc7610ecd1eb4cd16e0b5a1Vendor (CNA)
Linux Linux295dd295e2137e10e9a5b1891d97e0f08de76f03Vendor (CNA)
Linux Linux2dc2fffc704a4365cae1aae078ba62223aaeff93Vendor (CNA)
Linux Linux466b474a8deb0c93b5280c6d261e5eda6482eca7Vendor (CNA)
Linux Linux95651461cf77cc6590fa08c87667717e5dcfa55dVendor (CNA)
Linux Linuxa5cdd2407dd890f741f59b8367e4c6c101cce154Vendor (CNA)
Linux Linuxba56f88aab18d982f2a21f11390f4d8a8897782aVendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.06.6.152.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.187-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.107-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

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References

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records