Linux Kernel up to 6.13.6 Ppp Driver bpf_program uninitialized pointer

CVSS Meta Temp Score
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CTI Interest Score
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5.3$0-$5k0.00

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.13.6. It has been classified as problematic. Affected by this vulnerability is the function bpf_program of the component Ppp Driver. Performing a manipulation results in uninitialized pointer. This vulnerability was named CVE-2025-21922. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability classified as problematic has been found in Linux Kernel up to 6.13.6. This affects the function bpf_program of the component Ppp Driver. The manipulation with an unknown input leads to a uninitialized pointer vulnerability. CWE is classifying the issue as CWE-824. The product accesses or uses a pointer that has not been initialized. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: ppp: Fix KMSAN uninit-value warning with bpf Syzbot caught an "KMSAN: uninit-value" warning [1], which is caused by the ppp driver not initializing a 2-byte header when using socket filter. The following code can generate a PPP filter BPF program: ''' struct bpf_program fp; pcap_t *handle; handle = pcap_open_dead(DLT_PPP_PPPD, 65535); pcap_compile(handle, &fp, "ip and outbound", 0, 0); bpf_dump(&fp, 1); ''' Its output is: ''' (000) ldh [2] (001) jeq #0x21 jt 2 jf 5 (002) ldb [0] (003) jeq #0x1 jt 4 jf 5 (004) ret #65535 (005) ret #0 ''' Wen can find similar code at the following link: https://github.com/ppp-project/ppp/blob/master/pppd/options.c#L1680 The maintainer of this code repository is also the original maintainer of the ppp driver. As you can see the BPF program skips 2 bytes of data and then reads the 'Protocol' field to determine if it's an IP packet. Then it read the first byte of the first 2 bytes to determine the direction. The issue is that only the first byte indicating direction is initialized in current ppp driver code while the second byte is not initialized. For normal BPF programs generated by libpcap, uninitialized data won't be used, so it's not a problem. However, for carefully crafted BPF programs, such as those generated by syzkaller [2], which start reading from offset 0, the uninitialized data will be used and caught by KMSAN. [1] https://syzkaller.appspot.com/bug?extid=853242d9c9917165d791 [2] https://syzkaller.appspot.com/text?tag=ReproC&x=11994913980000

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2025-21922 since 12/29/2024. Technical details of the vulnerability are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 234309 (Debian dsa-5900 : affs-modules-6.1.0-28-4kc-malta-di - security update), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.4.291, 5.10.235, 5.15.179, 6.1.131, 6.6.83, 6.12.19 or 6.13.7 eliminates this vulnerability. Applying the patch d685096c8129c9a92689975193e268945fd21dbf/2f591cb158807bdcf424f66f1fbfa6e4e50f3757/4e2191b0fd0c064d37b0db67396216f2d4787e0f/3de809a768464528762757e433cd50de35bcb3c1/1eacd47636a9de5bee25d9d5962dc538a82d9f0b/8aa8a40c766b3945b40565a70349d5581458ff63/c036f5f2680cbdabdbbace86baee3c83721634d6/4c2d14c40a68678d885eab4008a0129646805bae is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (234309) and CERT Bund (WID-SEC-2025-0683). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Affected

  • Google Container-Optimized OS
  • Debian Linux
  • Amazon Linux 2
  • Red Hat Enterprise Linux
  • Ubuntu Linux
  • SUSE Linux
  • Oracle Linux
  • RESF Rocky Linux
  • Dell Avamar
  • Open Source Linux Kernel
  • SolarWinds Security Event Manager
  • Dell NetWorker
  • Dell Secure Connect Gateway
  • IBM Security Verify Access

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.5
VulDB Meta Temp Score: 5.3

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
VulDB Vector: 🔍
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔍
VulDB Temp Score: 🔍
VulDB Reliability: 🔍

Exploitinginfo

Class: Uninitialized pointer
CWE: CWE-824 / CWE-908
CAPEC: 🔍
ATT&CK: 🔍

Physical: No
Local: No
Remote: Partially

Availability: 🔍
Status: Not defined

EPSS Score: 🔍
EPSS Percentile: 🔍

Price Prediction: 🔍
Current Price Estimation: 🔍

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Nessus ID: 234309
Nessus Name: Debian dsa-5900 : affs-modules-6.1.0-28-4kc-malta-di - security update

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔍

Upgrade: Kernel 5.4.291/5.10.235/5.15.179/6.1.131/6.6.83/6.12.19/6.13.7
Patch: d685096c8129c9a92689975193e268945fd21dbf/2f591cb158807bdcf424f66f1fbfa6e4e50f3757/4e2191b0fd0c064d37b0db67396216f2d4787e0f/3de809a768464528762757e433cd50de35bcb3c1/1eacd47636a9de5bee25d9d5962dc538a82d9f0b/8aa8a40c766b3945b40565a70349d5581458ff63/c036f5f2680cbdabdbbace86baee3c83721634d6/4c2d14c40a68678d885eab4008a0129646805bae

Timelineinfo

12/29/2024 🔍
04/01/2025 +92 days 🔍
04/01/2025 +0 days 🔍
02/01/2026 +306 days 🔍

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2025-21922 (🔍)
GCVE (CVE): GCVE-0-2025-21922
GCVE (VulDB): GCVE-100-302643
CERT Bund: WID-SEC-2025-0683 - Linux Kernel: Mehrere Schwachstellen

Entryinfo

Created: 04/01/2025 19:04
Updated: 02/01/2026 06:25
Changes: 04/01/2025 19:04 (58), 04/14/2025 13:56 (2), 07/20/2025 02:06 (7), 07/21/2025 19:48 (1), 10/26/2025 19:49 (1), 02/01/2026 06:25 (1)
Complete: 🔍
Cache ID: 216::103

Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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