CVE-2025-21922

Service interruption via uninitialized PPP filter header

Published Apr 1, 2025 · Updated May 11, 2026

Use of uninitialized data in the Linux kernel PPP driver allows local users to interrupt service through a crafted socket filter. The socket-filter path in drivers/net/ppp/ppp_generic.c initializes only the direction byte of a two-byte pseudo-header before BPF can read both bytes. Triggering requires local access and a deliberately constructed BPF program that reads from offset zero; ordinary libpcap filters do not consume the uninitialized byte.

CVSS severity5.5
Medium
EPSS probability0.23%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Use of uninitialized data in the Linux kernel PPP driver allows local users to interrupt service through a crafted socket filter. The socket-filter path in drivers/net/ppp/ppp_generic.c initializes only the direction byte of a two-byte pseudo-header before BPF can read both bytes. Triggering requires local access and a deliberately constructed BPF program that reads from offset zero; ordinary libpcap filters do not consume the uninitialized byte.

The record

CVE
CVE-2025-21922
Published
Apr 1, 2025
Updated
May 11, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-908
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 1, 2025CVE 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=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1eacd47636a9de5bee25d9d5962dc538a82d9f0b
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2f591cb158807bdcf424f66f1fbfa6e4e50f3757
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3de809a768464528762757e433cd50de35bcb3c1
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4c2d14c40a68678d885eab4008a0129646805bae
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4e2191b0fd0c064d37b0db67396216f2d4787e0f
  6. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <8aa8a40c766b3945b40565a70349d5581458ff63
  7. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c036f5f2680cbdabdbbace86baee3c83721634d6
  8. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d685096c8129c9a92689975193e268945fd21dbf
  9. Affected versionversion=2.6.12

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <1eacd47636a9de5bee25d9d5962dc538a82d9f0b; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <2f591cb158807bdcf424f66f1fbfa6e4e50f3757; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3de809a768464528762757e433cd50de35bcb3c1; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4c2d14c40a68678d885eab4008a0129646805bae; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <4e2191b0fd0c064d37b0db67396216f2d4787e0f; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <8aa8a40c766b3945b40565a70349d5581458ff63; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <c036f5f2680cbdabdbbace86baee3c83721634d6; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <d685096c8129c9a92689975193e268945fd21dbf; version=2.6.12

Published CVSS scores

5.5NISTCVSS: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-908Use of Uninitialized Resource

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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