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

Published: 2025-02-27 Last update: 2026-05-12 Assigner: 416baaa9-dc9f-4396-8d5f-8c081fb06d67 Source: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

Conclusion & alert: CVE-2025-21787 is rated Low Risk (23.7/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.02%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-21787

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-04-17 0.05% 0.02% -0.03%
2 2025-11-13 0.05% 0.05% +0.00%
3 2025-11-04 0.05%

Full EPSS history (7 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-21787

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.5 3.1 MEDIUM
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:L)
They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
1.8 3.6 [email protected]

Weakness enumeration for CVE-2025-21787

GitHub Security Advisory for CVE-2025-21787

GHSA-mh6r-68r2-78qw · Severity: medium — In the Linux kernel, the following vulnerability has been resolved: team: better...

OS Trackers for CVE-2025-21787

vendor priority summary link
debian not yet assigned CVE-2025-21787 not yet assigned priority: Debian including 2 source packages (linux, linux-6.1), 6 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 6. https://security-tracker.debian.org/tracker/CVE-2025-21787
redhat medium https://access.redhat.com/security/cve/CVE-2025-21787
suse medium https://www.suse.com/security/cve/CVE-2025-21787/
ubuntu medium CVE-2025-21787 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1551 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1145, released 189, ignored 154, not-affected 43, needed 20. https://ubuntu.com/security/CVE-2025-21787

Affected software / configurations for CVE-2025-21787

Vendor Product Version Raw CPE
linux linux_kernel >= 3.3, < 6.1.129 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.2, < 6.6.79 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.7, < 6.12.16 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel >= 6.13, < 6.13.4 cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linux linux_kernel 6.14 cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:*
linux linux_kernel 6.14 cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:*

References for CVE-2025-21787

URL Tags
https://git.kernel.org/stable/c/4236bf4716589558cc0f3c3612642b2c2141b04e Mailing List Patch
https://git.kernel.org/stable/c/4512482e4805dd30bc77dec511f2a2edba5cb868 Mailing List Patch
https://git.kernel.org/stable/c/5bef3ac184b5626ea62385d6b82a1992b89d7940 Mailing List Patch
https://git.kernel.org/stable/c/7c30483d0f6bdb2230e10e3e4be5167927eac7a0
https://git.kernel.org/stable/c/7f5af50f3aa0af8cbef9fb76fffeed69e8143f59
https://git.kernel.org/stable/c/8401cade1918281177974b32c925afdce750d292 Mailing List Patch
https://git.kernel.org/stable/c/d071a91fa614ecdf760c29f61f6a7bfb7df796d6 Mailing List Patch
https://git.kernel.org/stable/c/f443687ad20c70320d1248f35f57bf46cac8df0a
https://lists.debian.org/debian-lts-announce/2025/03/msg00028.html
https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html
https://cert-portal.siemens.com/productcert/html/ssa-265688.html
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