CVE-2025-39847

Local denial of service via PPP memory leak

Published Sep 19, 2025 · Updated Sep 19, 2025

Memory leak in the Linux kernel PPP subsystem allows local users to exhaust memory when packet-buffer allocation fails during compression. The pad_compress_skb caller overwrites its sole reference to the original skb when alloc_skb returns NULL, so the drop path cannot free that buffer. Exploitation requires local low-privilege access, PPP compression, and repeated allocation failures; leaked kernel memory exhausts resources and interrupts service.

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

What happened

Memory leak in the Linux kernel PPP subsystem allows local users to exhaust memory when packet-buffer allocation fails during compression. The pad_compress_skb caller overwrites its sole reference to the original skb when alloc_skb returns NULL, so the drop path cannot free that buffer. Exploitation requires local low-privilege access, PPP compression, and repeated allocation failures; leaked kernel memory exhausts resources and interrupts service.

The record

CVE
CVE-2025-39847
Published
Sep 19, 2025
Updated
Sep 19, 2025
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-401, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 19, 2025CVE publishedPublication date reported by the CVE source.
  2. Sep 19, 2025Record 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=2.6.15
  2. Affected versionversion=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <0b21e9cd4559102da798bdcba453b64ecd7be7ee
  3. Affected versionversion=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <1d8b354eafb8876d8bdb1bef69c7d2438aacfbe8
  4. Affected versionversion=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <33a5bac5f14772730d2caf632ae97b6c2ee95044
  5. Affected versionversion=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <4844123fe0b853a4982c02666cb3fd863d701d50
  6. Affected versionversion=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <631fc8ab5beb9e0ec8651fb9875b9a968e7b4ae4
  7. Affected versionversion=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <85c1c86a67e09143aa464e9bf09c397816772348
  8. Affected versionversion=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <87a35a36742df328d0badf4fbc2e56061c15846c
  9. Affected versionversion=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <9ca6a040f76c0b149293e430dabab446f3fc8ab7

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.15; version=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <0b21e9cd4559102da798bdcba453b64ecd7be7ee; version=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <1d8b354eafb8876d8bdb1bef69c7d2438aacfbe8; version=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <33a5bac5f14772730d2caf632ae97b6c2ee95044; version=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <4844123fe0b853a4982c02666cb3fd863d701d50; version=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <631fc8ab5beb9e0ec8651fb9875b9a968e7b4ae4; version=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <85c1c86a67e09143aa464e9bf09c397816772348; version=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <87a35a36742df328d0badf4fbc2e56061c15846c; version=b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c <9ca6a040f76c0b149293e430dabab446f3fc8ab7

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
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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