CVE-2021-47345

Kernel-memory exhaustion via repeated RDMA route resolution

Published May 21, 2024 · Updated May 11, 2026

Memory leakage in the Linux kernel's RDMA connection manager allows local users to exhaust kernel memory through repeated route resolution. The cma_resolve_ib_route() path replaces route->path_rec with a new allocation after RDMA_CM_EVENT_ROUTE_ERROR returns the same rdma_cm_id to the address-resolved state, losing the prior allocation. Exploitation requires low-privileged local access and repeated route-resolution calls; the bounded consequence is availability loss from kernel-memory exhaustion.

CVSS severity5.5
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Memory leakage in the Linux kernel's RDMA connection manager allows local users to exhaust kernel memory through repeated route resolution. The cma_resolve_ib_route() path replaces route->path_rec with a new allocation after RDMA_CM_EVENT_ROUTE_ERROR returns the same rdma_cm_id to the address-resolved state, losing the prior allocation. Exploitation requires low-privileged local access and repeated route-resolution calls; the bounded consequence is availability loss from kernel-memory exhaustion.

The record

CVE
CVE-2021-47345
Published
May 21, 2024
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499.001
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 21, 2024CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.18
  2. Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <032c68b4f5be128a2167f35b558b7cec88fe4972
  3. Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <07583ba2e2d8947c3d365d97608cb436510885ac
  4. Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <3d08b5917984f737f32d5bee9737b9075c3895c6
  5. Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <40b613db3a95bc27998e4097d74c2f7e5d083a0b
  6. Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <4893c938f2a140a74be91779e45e4a7fa111198f
  7. Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <74f160ead74bfe5f2b38afb4fcf86189f9ff40c9
  8. Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <e2da8ce2a9543f3ca5c93369bd1fe6eeb572101a
  9. Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <e4e062da082a199357ba4911145f331d40139ad8
  10. Affected versionversion=e51060f08a61965c4dd91516d82fe90617152590 <f4f553d67236145fa5fd203ed7b35b9377e19939

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.18; version=e51060f08a61965c4dd91516d82fe90617152590 <032c68b4f5be128a2167f35b558b7cec88fe4972; version=e51060f08a61965c4dd91516d82fe90617152590 <07583ba2e2d8947c3d365d97608cb436510885ac; version=e51060f08a61965c4dd91516d82fe90617152590 <3d08b5917984f737f32d5bee9737b9075c3895c6; version=e51060f08a61965c4dd91516d82fe90617152590 <40b613db3a95bc27998e4097d74c2f7e5d083a0b; version=e51060f08a61965c4dd91516d82fe90617152590 <4893c938f2a140a74be91779e45e4a7fa111198f; version=e51060f08a61965c4dd91516d82fe90617152590 <74f160ead74bfe5f2b38afb4fcf86189f9ff40c9; version=e51060f08a61965c4dd91516d82fe90617152590 <e2da8ce2a9543f3ca5c93369bd1fe6eeb572101a; version=e51060f08a61965c4dd91516d82fe90617152590 <e4e062da082a199357ba4911145f331d40139ad8; version=e51060f08a61965c4dd91516d82fe90617152590 <f4f553d67236145fa5fd203ed7b35b9377e19939

Published CVSS scores

5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-401Missing Release of Memory after Effective Lifetime
T1499.001OS Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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