CVE-2025-39847: debian linux — Fix

Description

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.

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CVSS v3.1 Score

5.5

MEDIUM

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

Weakness Type (CWE)

CWE-401 CWE-401

Affected Products

Vendor	Product	Versions
linux	linux_kernel	2.6.15 — 5.4.299
linux	linux_kernel	5.5 — 5.10.243
linux	linux_kernel	5.11 — 5.15.192
linux	linux_kernel	5.16 — 6.1.151
linux	linux_kernel	6.2 — 6.6.105
linux	linux_kernel	6.7 — 6.12.46
linux	linux_kernel	6.13 — 6.16.6
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
linux	linux_kernel	All
debian	debian_linux	All

References

Advisories & Patches

https://git.kernel.org/stable/c/0b21e9cd4559102da798bdcba453b64ecd7be7ee https://git.kernel.org/stable/c/1d8b354eafb8876d8bdb1bef69c7d2438aacfbe8 https://git.kernel.org/stable/c/33a5bac5f14772730d2caf632ae97b6c2ee95044 https://git.kernel.org/stable/c/4844123fe0b853a4982c02666cb3fd863d701d50 https://git.kernel.org/stable/c/631fc8ab5beb9e0ec8651fb9875b9a968e7b4ae4 https://git.kernel.org/stable/c/85c1c86a67e09143aa464e9bf09c397816772348 https://git.kernel.org/stable/c/87a35a36742df328d0badf4fbc2e56061c15846c https://git.kernel.org/stable/c/9ca6a040f76c0b149293e430dabab446f3fc8ab7

Other References

https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html https://cert-portal.siemens.com/productcert/html/ssa-032379.html

Frequently Asked Questions

What is CVE-2025-39847? +

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. It has a CVSS v3.1 base score of 5.5 (MEDIUM).

How severe is CVE-2025-39847? +

CVE-2025-39847 has a CVSS v3.1 score of 5.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance.

What products are affected by CVE-2025-39847? +

CVE-2025-39847 affects products from debian, linux, specifically: debian_linux, linux_kernel. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-39847? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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CVE-2025-39847