CVE Intelligence
Medium Memory corruption

CVE-2025-21707 — mptcp: consolidate suboption status

In the Linux kernel, the following vulnerability has been resolved: mptcp: consolidate suboption status MPTCP maintains the received sub-options status is the bitmask carrying the received suboptions and in several bitfields carrying per suboption additional info. Zeroing the bitmask before parsing is not enough to ensure a consistent status, and the MPTCP code has to additionally clear some bitfiled depending on the actually parsed suboption. The above schema is fragile, and syzbot managed to trigger a path where a relevant bitfield is not cleared/initialized: BUG: KMSAN: uninit-value in __mptcp_expand_seq net/mptcp/options.c:1030 [inline] BUG: KMSAN: uninit-value in mptcp_expand_seq net/mptcp/protocol.h:864 [inline] BUG: KMSAN: uninit-value in ack_update_msk net/mptcp/options.c:1060 [inline] BUG: KMSAN: uninit-value in mptcp_incoming_options+0x2036/0x3d30 net/mptcp/options.c:1209 __mptcp_expand_seq net/mptcp/options.c:1030 [inline] mptcp_expand_seq net/mptcp/protocol.h:864 [inline] ack_update_msk net/mptcp/options.c:1060 [inline] mptcp_incoming_options+0x2036/0x3d30 net/mptcp/options.c:1209 tcp_data_queue+0xb4/0x7be0 net/ipv4/tcp_input.c:5233 tcp_rcv_established+0x1061/0x2510 net/ipv4/tcp_input.c:6264 tcp_v4_do_rcv+0x7f3/0x11a0 net/ipv4/tcp_ipv4.c:1916 tcp_v4_rcv+0x51df/0x5750 net/ipv4/tcp_ipv4.c:2351 ip_protocol_deliver_rcu+0x2a3/0x13d0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x336/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:314 [inline] ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:460 [inline] ip_rcv_finish+0x4a2/0x520 net/ipv4/ip_input.c:447 NF_HOOK include/linux/netfilter.h:314 [inline] ip_rcv+0xcd/0x380 net/ipv4/ip_input.c:567 __netif_receive_skb_one_core net/core/dev.c:5704 [inline] __netif_receive_skb+0x319/0xa00 net/core/dev.c:5817 process_backlog+0x4ad/0xa50 net/core/dev.c:6149 __napi_poll+0xe7/0x980 net/core/dev.c:6902 napi_poll net/core/dev.c:6971 [inline] net_rx_action+0xa5a/0x19b0 net/core/dev.c:7093 handle_softirqs+0x1a0/0x7c0 kernel/softirq.c:561 __do_softirq+0x14/0x1a kernel/softirq.c:595 do_softirq+0x9a/0x100 kernel/softirq.c:462 __local_bh_enable_ip+0x9f/0xb0 kernel/softirq.c:389 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:919 [inline] __dev_queue_xmit+0x2758/0x57d0 net/core/dev.c:4493 dev_queue_xmit include/linux/netdevice.h:3168 [inline] neigh_hh_output include/net/neighbour.h:523 [inline] neigh_output include/net/neighbour.h:537 [inline] ip_finish_output2+0x187c/0x1b70 net/ipv4/ip_output.c:236 __ip_finish_output+0x287/0x810 ip_finish_output+0x4b/0x600 net/ipv4/ip_output.c:324 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip_output+0x15f/0x3f0 net/ipv4/ip_output.c:434 dst_output include/net/dst.h:450 [inline] ip_local_out net/ipv4/ip_output.c:130 [inline] __ip_queue_xmit+0x1f2a/0x20d0 net/ipv4/ip_output.c:536 ip_queue_xmit+0x60/0x80 net/ipv4/ip_output.c:550 __tcp_transmit_skb+0x3cea/0x4900 net/ipv4/tcp_output.c:1468 tcp_transmit_skb net/ipv4/tcp_output.c:1486 [inline] tcp_write_xmit+0x3b90/0x9070 net/ipv4/tcp_output.c:2829 __tcp_push_pending_frames+0xc4/0x380 net/ipv4/tcp_output.c:3012 tcp_send_fin+0x9f6/0xf50 net/ipv4/tcp_output.c:3618 __tcp_close+0x140c/0x1550 net/ipv4/tcp.c:3130 __mptcp_close_ssk+0x74e/0x16f0 net/mptcp/protocol.c:2496 mptcp_close_ssk+0x26b/0x2c0 net/mptcp/protocol.c:2550 mptcp_pm_nl_rm_addr_or_subflow+0x635/0xd10 net/mptcp/pm_netlink.c:889 mptcp_pm_nl_rm_subflow_received net/mptcp/pm_netlink.c:924 [inline] mptcp_pm_flush_addrs_and_subflows net/mptcp/pm_netlink.c:1688 [inline] mptcp_nl_flush_addrs_list net/mptcp/pm_netlink.c:1709 [inline] mptcp_pm_nl_flush_addrs_doit+0xe10/0x1630 net/mptcp/pm_netlink.c:1750 genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline] ---truncated---

Published Feb 26, 2025 · Updated Oct 14, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: Linux

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 0.5% (30-day exploitation probability)+6
  • Technical severity (medium)+3

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
0.48%
ahead of 40% of scored CVEs · Oct 14, 2026
Affects
Linux
Linux and 1 more
CVSS base
5.5
Medium · 4 source(s)
Prioritization reference: 9.8 provisional

Remediation

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

  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)

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.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
  2. Apply the fixed version or the patch documented under Remediation.
  3. Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux ≥ 84dfe3677a6f45b3d0dfdd564e55717a1a5e60cc and < 3a7fda57b0f91f7ea34476b165f91a92feb17c96≥ 84dfe3677a6f45b3d0dfdd564e55717a1a5e60cc and < 3b5332d416d151a15742d1b16e7319368e3cc5c6≥ 84dfe3677a6f45b3d0dfdd564e55717a1a5e60cc and < 7f6c72b8ef8130760710e337dc8fbe7263954884≥ 84dfe3677a6f45b3d0dfdd564e55717a1a5e60cc and < 6169e942370b4b6f9442d35c51519bf6c346843b≥ 84dfe3677a6f45b3d0dfdd564e55717a1a5e60cc and < ba0518f9e8688cd4fcb569e8df2a74874b4f3894≥ 84dfe3677a6f45b3d0dfdd564e55717a1a5e60cc and < c86b000782daba926c627d2fa00c3f60a75e7472version 5.11 Vulnerable CVE Program (cve.org) e CISA ADP
Linux Linux Kernel ≥ 5.11 and < 6.1.129≥ 6.2 and < 6.6.76≥ 6.7 and < 6.12.13≥ 6.13 and < 6.13.2 Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
9.8 CVSS 3.1 Critical 3.9 5.9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database
9.8 CVSS 3.1 Critical — — Linux via CVE Program (cve.org) e CISA ADP
5.5 CVSS 3.1 Medium 1.8 3.6 nvd@nist.gov via NIST National Vulnerability Database
5.5 CVSS 3.1 Medium — — GitHub, Inc. via GitHub Security Advisories
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov)
Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 9.8 (416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-908 · Use of Uninitialized Resource

Other CVEs with this weakness →

Detection

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

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
  • Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · linux/linux
    Oct 14, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 14, 2026
  • Fix documented
    Oct 14, 2026 · NIST National Vulnerability Database
  • Affected products added · linux/linux kernel
    Oct 14, 2026 · NIST National Vulnerability Database
  • CVSS changed · 5.5
    Oct 14, 2026 · NIST National Vulnerability Database
  • Source status changed · → Modified
    Oct 14, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 14, 2026 · Alertas do Telegram
  • 2025
  • CVE published
    Feb 26, 2025 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 14, 2026 – Oct 14, 2026
  • 1× Official description updated · Oct 14, 2026 – Oct 14, 2026

References

12 on the record

Elsewhere on this site

Linux
every CVE for this vendor
Memory corruption
same class
CWE-908
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-99999 ipv4: validate checksum_start before completing checksum 9h
  • CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 9h
  • CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
  • CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
  • CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
  • CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 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 CISA SSVC assessment.
  • 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-2025-21707 is "mptcp: consolidate suboption status", rated Medium. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.5 describes technical severity. EPSS 0.48% 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.

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