LiveActive security incident?Get immediate response
CVE Record

CVE-2025-21892: RDMA/mlx5: Fix the recovery flow of the UMR QP

In the Linux kernel, the following vulnerability has been resolved: RDMA/mlx5: Fix the recovery flow of the UMR QP This patch addresses an issue in the recovery flow of the UMR QP, ensuring tasks do not get stuck, as highlighted by the call trace [1]. During recovery, before transitioning the QP to the RESET state, the software must wait for all outstanding WRs to complete. Failing to do so can cause the firmware to skip sending some flushed CQEs with errors and simply discard them upon the RESET, as per the IB specification. This race condition can result in lost CQEs and tasks becoming stuck. To resolve this, the patch sends a final WR which serves only as a barrier before moving the QP state to RESET. Once a CQE is received for that final WR, it guarantees that no outstanding WRs remain, making it safe to transition the QP to RESET and subsequently back to RTS, restoring proper functionality. Note: For the barrier WR, we simply reuse the failed and ready WR. Since the QP is in an error state, it will only receive IB_WC_WR_FLUSH_ERR. However, as it serves only as a barrier we don't care about its status. [1] INFO: task rdma_resource_l:1922 blocked for more than 120 seconds. Tainted: G W 6.12.0-rc7+ #1626 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. task:rdma_resource_l state:D stack:0 pid:1922 tgid:1922 ppid:1369 flags:0x00004004 Call Trace: <TASK> __schedule+0x420/0xd30 schedule+0x47/0x130 schedule_timeout+0x280/0x300 ? mark_held_locks+0x48/0x80 ? lockdep_hardirqs_on_prepare+0xe5/0x1a0 wait_for_completion+0x75/0x130 mlx5r_umr_post_send_wait+0x3c2/0x5b0 [mlx5_ib] ? __pfx_mlx5r_umr_done+0x10/0x10 [mlx5_ib] mlx5r_umr_revoke_mr+0x93/0xc0 [mlx5_ib] __mlx5_ib_dereg_mr+0x299/0x520 [mlx5_ib] ? _raw_spin_unlock_irq+0x24/0x40 ? wait_for_completion+0xfe/0x130 ? rdma_restrack_put+0x63/0xe0 [ib_core] ib_dereg_mr_user+0x5f/0x120 [ib_core] ? lock_release+0xc6/0x280 destroy_hw_idr_uobject+0x1d/0x60 [ib_uverbs] uverbs_destroy_uobject+0x58/0x1d0 [ib_uverbs] uobj_destroy+0x3f/0x70 [ib_uverbs] ib_uverbs_cmd_verbs+0x3e4/0xbb0 [ib_uverbs] ? __pfx_uverbs_destroy_def_handler+0x10/0x10 [ib_uverbs] ? __lock_acquire+0x64e/0x2080 ? mark_held_locks+0x48/0x80 ? find_held_lock+0x2d/0xa0 ? lock_acquire+0xc1/0x2f0 ? ib_uverbs_ioctl+0xcb/0x170 [ib_uverbs] ? __fget_files+0xc3/0x1b0 ib_uverbs_ioctl+0xe7/0x170 [ib_uverbs] ? ib_uverbs_ioctl+0xcb/0x170 [ib_uverbs] __x64_sys_ioctl+0x1b0/0xa70 do_syscall_64+0x6b/0x140 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f99c918b17b RSP: 002b:00007ffc766d0468 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007ffc766d0578 RCX: 00007f99c918b17b RDX: 00007ffc766d0560 RSI: 00000000c0181b01 RDI: 0000000000000003 RBP: 00007ffc766d0540 R08: 00007f99c8f99010 R09: 000000000000bd7e R10: 00007f99c94c1c70 R11: 0000000000000246 R12: 00007ffc766d0530 R13: 000000000000001c R14: 0000000040246a80 R15: 0000000000000000 </TASK>

UnknownCVSS not scoredNot KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This Linux kernel issue can cause RDMA tasks using the mlx5 driver to become stuck during recovery. For organizations using Mellanox mlx5 RDMA hardware, the business risk is availability disruption, not confirmed data theft or remote compromise based on the provided sources.

Executive priority

Treat this as a targeted availability risk for RDMA-dependent infrastructure. Patch affected Linux kernels through normal emergency-capable maintenance, with higher urgency where RDMA supports production storage, compute, or low-latency services.

Technical view

The flaw is a race in RDMA/mlx5 UMR QP recovery. Resetting the QP before all outstanding work requests complete can make firmware discard flushed CQEs, leaving completions lost and tasks blocked. The fix adds a barrier WR before RESET.

Likely exposure

Exposure appears limited to Linux systems using RDMA with the mlx5_ib driver and UMR QP paths. General Linux servers without mlx5 RDMA use are unlikely to be affected by this specific failure mode.

Exploitation context

The source bundle does not show active exploitation, KEV listing, public exploit details, CVSS, or a CWE. Evidence describes a kernel recovery race causing hung tasks, with a call trace from Linux 6.12.0-rc7.

Researcher notes

The affected-version data in the bundle is inconsistent and should be validated against downstream vendor advisories. The source evidence supports a lost-CQE recovery race and a barrier-WR fix, but not exploitability beyond the described hang.

Mitigation direction

  • Apply vendor kernel updates containing the referenced stable Linux fixes.
  • Prioritize RDMA-enabled hosts using Mellanox mlx5 hardware or mlx5_ib.
  • Check distribution advisories for backported CVE-2025-21892 fixes.
  • Consider maintenance windows for high-performance computing or storage nodes using RDMA.

Validation and detection

  • Inventory Linux hosts with RDMA, mlx5 hardware, or mlx5_ib usage.
  • Compare running kernel packages against vendor advisories for CVE-2025-21892.
  • Review kernel logs for hung RDMA tasks or mlx5_ib UMR traces.
  • Confirm updated kernels include one of the referenced stable commits or vendor backports.
Prepared
Confidence
medium
Sources
5

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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cve · low confidence lookup

CVE-2025-21892 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
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
0ADP providers
4Source 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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux158e71bb69e368b8b33e8b7c4ac8c111da0c1ae2, 158e71bb69e368b8b33e8b7c4ac8c111da0c1ae2, 158e71bb69e368b8b33e8b7c4ac8c111da0c1ae2, d8f7bff9a42627d37f4ecffeb01e44db42167175, 5.19.10unaffected
LinuxLinux6.0, 0, 6.12.18, 6.13.6, 6.14affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.