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CVE Record

CVE-2025-21787: team: better TEAM_OPTION_TYPE_STRING validation

In the Linux kernel, the following vulnerability has been resolved: team: better TEAM_OPTION_TYPE_STRING validation syzbot reported following splat [1] Make sure user-provided data contains one nul byte. [1] BUG: KMSAN: uninit-value in string_nocheck lib/vsprintf.c:633 [inline] BUG: KMSAN: uninit-value in string+0x3ec/0x5f0 lib/vsprintf.c:714 string_nocheck lib/vsprintf.c:633 [inline] string+0x3ec/0x5f0 lib/vsprintf.c:714 vsnprintf+0xa5d/0x1960 lib/vsprintf.c:2843 __request_module+0x252/0x9f0 kernel/module/kmod.c:149 team_mode_get drivers/net/team/team_core.c:480 [inline] team_change_mode drivers/net/team/team_core.c:607 [inline] team_mode_option_set+0x437/0x970 drivers/net/team/team_core.c:1401 team_option_set drivers/net/team/team_core.c:375 [inline] team_nl_options_set_doit+0x1339/0x1f90 drivers/net/team/team_core.c:2662 genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline] genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x1214/0x12c0 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2543 genl_rcv+0x40/0x60 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1322 [inline] netlink_unicast+0xf52/0x1260 net/netlink/af_netlink.c:1348 netlink_sendmsg+0x10da/0x11e0 net/netlink/af_netlink.c:1892 sock_sendmsg_nosec net/socket.c:718 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:733 ____sys_sendmsg+0x877/0xb60 net/socket.c:2573 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2627 __sys_sendmsg net/socket.c:2659 [inline] __do_sys_sendmsg net/socket.c:2664 [inline] __se_sys_sendmsg net/socket.c:2662 [inline] __x64_sys_sendmsg+0x212/0x3c0 net/socket.c:2662 x64_sys_call+0x2ed6/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue is a validation bug in the network team driver. User-provided string data was not guaranteed to contain a null terminator, causing uninitialized kernel memory use in a reported syzbot crash path. The public data does not provide a CVSS score, confirmed impact beyond the crash trace, or evidence of active exploitation.

Executive priority

Treat as a normal kernel patching priority unless team driver use is widespread or exposed on critical infrastructure. There is no cited active exploitation, but kernel memory-safety bugs warrant timely maintenance because impact details may evolve as vendors assess affected builds.

Technical view

The flaw affects TEAM_OPTION_TYPE_STRING handling in drivers/net/team/team_core.c. The reported path reaches team_nl_options_set_doit through Generic Netlink and then vsnprintf/__request_module with an unterminated user-controlled string. The kernel fix ensures supplied string option data contains one NUL byte before use.

Likely exposure

Exposure is most relevant to Linux systems with affected kernel versions and the team network driver functionality present. The source bundle lists Linux kernel versions starting at 3.3 and fixed stable releases across 5.4, 5.10, 5.15, 6.1, 6.6, 6.12, 6.13, and 6.14 lines.

Exploitation context

No KEV listing or cited source in the bundle states active exploitation. The evidence is a syzbot-discovered kernel bug with a local kernel call trace via netlink sendmsg. The bundle does not establish remote exploitation, public exploit availability, or privilege impact.

Researcher notes

Key uncertainty remains impact severity. The trace shows uninitialized-value use from an unterminated TEAM_OPTION_TYPE_STRING reaching module request formatting. Avoid assuming code execution or remote reachability from the bundle alone. Validate branch-specific fixes through upstream stable commits and downstream vendor package notes.

Mitigation direction

  • Apply vendor kernel updates containing the referenced stable fixes.
  • Prioritize distro advisories for Debian LTS and other Linux vendors in use.
  • Disable or avoid Linux team driver functionality where unnecessary until patched.
  • For Siemens-managed products, follow the linked Siemens ProductCERT advisory.

Validation and detection

  • Inventory running kernel versions across Linux servers, appliances, and containers hosts.
  • Check whether team driver functionality is loaded or used on affected systems.
  • Confirm kernel packages include the relevant upstream stable commit for their branch.
  • Review Debian LTS and vendor advisories for backported package version mapping.
Prepared
Confidence
medium
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2025-21787 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
2ADP providers
12Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux3d249d4ca7d0ed6629a135ea1ea21c72286c0d80, 3d249d4ca7d0ed6629a135ea1ea21c72286c0d80, 3d249d4ca7d0ed6629a135ea1ea21c72286c0d80, 3d249d4ca7d0ed6629a135ea1ea21c72286c0d80, 3d249d4ca7d0ed6629a135ea1ea21c72286c0d80, 3d249d4ca7d0ed6629a135ea1ea21c72286c0d80, 3d249d4ca7d0ed6629a135ea1ea21c72286c0d80, 3d249d4ca7d0ed6629a135ea1ea21c72286c0d80unaffected
LinuxLinux3.3, 0, 5.4.291, 5.10.235, 5.15.179, 6.1.129, 6.6.79, 6.12.16, 6.13.4, 6.14affected
Weakness

CWE details

No CWE listed

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