CVE-2026-64436

Kernel memory disclosure and crash via uninitialized length

Published Jul 25, 2026 · Updated Jul 25, 2026

Uninitialized memory use in affected Linux Kernel releases allows local users to read kernel memory or crash the host through PF_KEY. pfkey_msg2xfrm_state() allocates an IPComp compression algorithm object without setting calg->alg_key_len, and xfrm_algo_clone() later trusts the stale value when sizing kmemdup(). The trigger requires local PF_KEY and XFRM netlink messages plus CAP_NET_ADMIN relative to the owning user namespace; an unprivileged local user can acquire that capability in new user and network namespaces.

CVSS severity7.1
High
EPSS probability0.13%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Uninitialized memory use in affected Linux Kernel releases allows local users to read kernel memory or crash the host through PF_KEY. pfkey_msg2xfrm_state() allocates an IPComp compression algorithm object without setting calg->alg_key_len, and xfrm_algo_clone() later trusts the stale value when sizing kmemdup(). The trigger requires local PF_KEY and XFRM netlink messages plus CAP_NET_ADMIN relative to the owning user namespace; an unprivileged local user can acquire that capability in new user and network namespaces.

The record

CVE
CVE-2026-64436
Published
Jul 25, 2026
Updated
Jul 25, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 25, 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=2.6.21
  2. Affected versionversion=80c9abaabf4283f7cf4a0b3597cd302506635b7f <01b9115b55018123ef2449ac4951f89147a8428e
  3. Affected versionversion=80c9abaabf4283f7cf4a0b3597cd302506635b7f <273c06b81d2e902b21acc801ae18c8276c8a9b69
  4. Affected versionversion=80c9abaabf4283f7cf4a0b3597cd302506635b7f <3f63d1752d90c0e28be931a48ab5d89bc97d637d
  5. Affected versionversion=80c9abaabf4283f7cf4a0b3597cd302506635b7f <58e82fc3dedb57b1432292504415b224fd2d6acb
  6. Affected versionversion=80c9abaabf4283f7cf4a0b3597cd302506635b7f <6de2a650917bedaaefd65b17cede83c5e2c1dedd
  7. Affected versionversion=80c9abaabf4283f7cf4a0b3597cd302506635b7f <cea34abc94b0a81e3a8b5cfb41cf45af37c2c67e
  8. Affected versionversion=80c9abaabf4283f7cf4a0b3597cd302506635b7f <d129c3177d7b1138fd5066fcc63a698b3ba415b0
  9. Affected versionversion=80c9abaabf4283f7cf4a0b3597cd302506635b7f <e8417353cbd078d10531ba3928e609c84ab09e6b

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.21; version=80c9abaabf4283f7cf4a0b3597cd302506635b7f <01b9115b55018123ef2449ac4951f89147a8428e; version=80c9abaabf4283f7cf4a0b3597cd302506635b7f <273c06b81d2e902b21acc801ae18c8276c8a9b69; version=80c9abaabf4283f7cf4a0b3597cd302506635b7f <3f63d1752d90c0e28be931a48ab5d89bc97d637d; version=80c9abaabf4283f7cf4a0b3597cd302506635b7f <58e82fc3dedb57b1432292504415b224fd2d6acb; version=80c9abaabf4283f7cf4a0b3597cd302506635b7f <6de2a650917bedaaefd65b17cede83c5e2c1dedd; version=80c9abaabf4283f7cf4a0b3597cd302506635b7f <cea34abc94b0a81e3a8b5cfb41cf45af37c2c67e; version=80c9abaabf4283f7cf4a0b3597cd302506635b7f <d129c3177d7b1138fd5066fcc63a698b3ba415b0; version=80c9abaabf4283f7cf4a0b3597cd302506635b7f <e8417353cbd078d10531ba3928e609c84ab09e6b

Published CVSS scores

7.1Linux kernel CNACVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/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

T1499Endpoint Denial of Service

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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