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NVD / CVE Program· CNA Linux

CVE-2025-39847: ppp: fix memory leak in pad_compress_skb

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: 0.16% (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 0b21e9cd4559102da798bdcba453b64ecd7be7ee, 1d8b354eafb8876d8bdb1bef69c7d2438aacfbe8, 33a5bac5f14772730d2caf632ae97b6c2ee95044; azl3 kernel 6.6.104.2-4 on Azure Linux 3.0 6.6.112.1-1; cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0 5.15.200.1-1.

Low priority for now. Upgrade to Linux Linux 0b21e9cd4559102da798bdcba453b64ecd7be7ee, 1d8b354eafb8876d8bdb1bef69c7d2438aacfbe8, 33a5bac5f14772730d2caf632ae97b6c2ee95044; azl3 kernel 6.6.104.2-4 on Azure Linux 3.0 6.6.112.1-1; cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.0 5.15.200.1-1 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 memory leak in pad_compress_skb If alloc_skb() fails in pad_compress_skb(), it returns NULL without releasing the old skb. The caller does: skb = pad_compress_skb(ppp, skb); if (!skb) goto drop; drop: kfree_skb(skb); When pad_compress_skb() returns NULL, the reference to the old skb is lost and kfree_skb(skb) ends up doing nothing, leading to a memory leak. Align pad_compress_skb() semantics with realloc(): only free the old skb if allocation and compression succeed. At the call site, use the new_skb variable so the original skb is not lost when pad_compress_skb() fails.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Sep 19, 2025
Updated
Nov 5, 2026
EPSS
0.1% · 5th 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 · 0.1%

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.

Follow CVE-2025-39847

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
debiandebian linux

Affected versions

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

  • debian debian linux11.0
  • linux linux kernel5.5 and later · before 5.10.243
  • linux linux kernel5.11 and later · before 5.15.192
  • linux linux kernel5.16 and later · before 6.1.151
  • linux linux kernel2.6.15 and later · before 5.4.299
  • linux linux kernel6.7 and later · before 6.12.46
  • linux linux kernel6.13 and later · before 6.16.6
  • linux linux kernel6.2 and later · before 6.6.105
  • linux linux kernel6.17

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

    • 2.6.15affected
    • b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c and later · before 9ca6a040f76c0b149293e430dabab446f3fc8ab7affected · git
    • b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c and later · before 87a35a36742df328d0badf4fbc2e56061c15846caffected · git
    • b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c and later · before 0b21e9cd4559102da798bdcba453b64ecd7be7eeaffected · git
    • b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c and later · before 1d8b354eafb8876d8bdb1bef69c7d2438aacfbe8affected · git
    • b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c and later · before 85c1c86a67e09143aa464e9bf09c397816772348affected · git
    • b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c and later · before 631fc8ab5beb9e0ec8651fb9875b9a968e7b4ae4affected · git
    • b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c and later · before 33a5bac5f14772730d2caf632ae97b6c2ee95044affected · git
    • b3f9b92a6ec1a9a5e4b4b36e484f2f62cc73277c and later · before 4844123fe0b853a4982c02666cb3fd863d701d50affected · git
    • before 2.6.15not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.153-16.1.153-1
Debian:13linuxbefore 6.12.48-16.12.48-1
Debian:14linuxbefore 6.16.6-16.16.6-1

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-2025-39845Sep 19, 2025 · x86/mm/64: define ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings()
    22Monitor
  • ← EarlierCVE-2025-39846Sep 19, 2025 · pcmcia: Fix a NULL pointer dereference in __iodyn_find_io_region()
    22Monitor
  • Later →CVE-2025-39848Sep 19, 2025 · ax25: properly unshare skbs in ax25_kiss_rcv()
    22Monitor

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 Linux0b21e9cd4559102da798bdcba453b64ecd7be7eeVendor (CNA)
Linux Linux1d8b354eafb8876d8bdb1bef69c7d2438aacfbe8Vendor (CNA)
Linux Linux33a5bac5f14772730d2caf632ae97b6c2ee95044Vendor (CNA)
Linux Linux4844123fe0b853a4982c02666cb3fd863d701d50Vendor (CNA)
Linux Linux631fc8ab5beb9e0ec8651fb9875b9a968e7b4ae4Vendor (CNA)
Linux Linux85c1c86a67e09143aa464e9bf09c397816772348Vendor (CNA)
Linux Linux87a35a36742df328d0badf4fbc2e56061c15846cVendor (CNA)
Linux Linux9ca6a040f76c0b149293e430dabab446f3fc8ab7Vendor (CNA)
azl3 kernel 6.6.104.2-4 on Azure Linux 3.06.6.112.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
cbl2 kernel 5.15.186.1-1 on CBL Mariner 2.05.15.200.1-1 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.153-1 · 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.

No nightly-computed relations.

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-401 · Missing Release of Memory after Effective Lifetime

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. SSVC exploitation— → none
  2. Fix✗ → ✓

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

References

Show all references (10 more)

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

All records