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NVD / CVE Program· CNA Linux

CVE-2025-21922: ppp: Fix KMSAN uninit-value warning with bpf

Noroxi assessment

Priority: Monitor (action score 22/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.23% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 1eacd47636a9de5bee25d9d5962dc538a82d9f0b, 2f591cb158807bdcf424f66f1fbfa6e4e50f3757, 3de809a768464528762757e433cd50de35bcb3c1; azl3 kernel 6.6.82.1-1 on Azure Linux 3.0 6.6.85.1-2; azl3 kernel 6.6.85.1-2 on Azure Linux 3.0 6.6.85.1-2.

Low priority for now. Upgrade to Linux Linux 1eacd47636a9de5bee25d9d5962dc538a82d9f0b, 2f591cb158807bdcf424f66f1fbfa6e4e50f3757, 3de809a768464528762757e433cd50de35bcb3c1; azl3 kernel 6.6.82.1-1 on Azure Linux 3.0 6.6.85.1-2; azl3 kernel 6.6.85.1-2 on Azure Linux 3.0 6.6.85.1-2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Apr 1, 2025
Updated
Jun 17, 2026
EPSS
0.2% · 14th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel2.6.12 and later · before 5.4.291
  • linux linux kernel5.5 and later · before 5.10.235
  • linux linux kernel5.11 and later · before 5.15.179
  • linux linux kernel5.16 and later · before 6.1.131
  • linux linux kernel6.2 and later · before 6.6.83
  • linux linux kernel6.7 and later · before 6.12.19
  • linux linux kernel6.13 and later · before 6.13.7
  • linux linux kernel6.14

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 2.6.12affected
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before d685096c8129c9a92689975193e268945fd21dbfaffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 2f591cb158807bdcf424f66f1fbfa6e4e50f3757affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 4e2191b0fd0c064d37b0db67396216f2d4787e0faffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 3de809a768464528762757e433cd50de35bcb3c1affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 1eacd47636a9de5bee25d9d5962dc538a82d9f0baffected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 8aa8a40c766b3945b40565a70349d5581458ff63affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before c036f5f2680cbdabdbbace86baee3c83721634d6affected · git
    • 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 4c2d14c40a68678d885eab4008a0129646805baeaffected · git
    • before 2.6.12not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.133-16.1.133-1
Debian:13linuxbefore 6.12.19-16.12.19-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2025-21918Apr 1, 2025 · usb: typec: ucsi: Fix NULL pointer access
    22Monitor
  • ← EarlierCVE-2025-21920Apr 1, 2025 · vlan: enforce underlying device type
    28Monitor
  • Later →CVE-2025-21923Apr 1, 2025 · HID: hid-steam: Fix use-after-free when detaching device
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux1eacd47636a9de5bee25d9d5962dc538a82d9f0bVendor (CNA)
Linux Linux2f591cb158807bdcf424f66f1fbfa6e4e50f3757Vendor (CNA)
Linux Linux3de809a768464528762757e433cd50de35bcb3c1Vendor (CNA)
Linux Linux4c2d14c40a68678d885eab4008a0129646805baeVendor (CNA)
Linux Linux4e2191b0fd0c064d37b0db67396216f2d4787e0fVendor (CNA)
Linux Linux8aa8a40c766b3945b40565a70349d5581458ff63Vendor (CNA)
Linux Linuxc036f5f2680cbdabdbbace86baee3c83721634d6Vendor (CNA)
Linux Linuxd685096c8129c9a92689975193e268945fd21dbfVendor (CNA)
azl3 kernel 6.6.82.1-1 on Azure Linux 3.06.6.85.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
azl3 kernel 6.6.85.1-2 on Azure Linux 3.06.6.85.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.176.3-3 on CBL Mariner 2.05.15.180.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.176.3-3 on CBL-Mariner 2.05.15.180.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.180.1-1 on CBL Mariner 2.05.15.180.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.133-1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

  • CVE-2024-50302133 days apartHID: core: zero-initialize the report bufferKEV
    52Plan
  • CVE-2026-52989449 days apartnvmet-tcp: propagate nvmet_tcp_build_pdu_iovec() errors to its callers
    39Monitor
  • CVE-2024-47685162 days apartnetfilter: nf_reject_ipv6: fix nf_reject_ip6_tcphdr_put()
    36Monitor
  • CVE-2026-53225450 days apartsctp: fix uninit-value in __sctp_rcv_asconf_lookup()
    36Monitor
  • CVE-2026-53170450 days apartaccel/ethosu: reject DMA commands with uninitialized length
    35Monitor
  • CVE-2026-43139400 days apartxfrm6: fix uninitialized saddr in xfrm6_get_saddr()
    34Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-908 · Use of Uninitialized Resource

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (9 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records