Answer in brief
CVE-2025-21921 records a Medium severity (CVSS 5.5) vulnerability in net: ethtool: netlink: Allow NULL nlattrs when getting a phy_device. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 5.5. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:6.14:rc1:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:6.14:rc2:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:6.14:rc3:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:6.14:rc4:*:*:*:*:*:* | Not reported | Not reported |
| cpe:2.3:o:linux:linux_kernel:6.14:rc5:*:*:*:*:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=c15e065b46dc4e19837275b826c1960d55564abd <639c70352958735addbba5ae7dd65985da96e061 || >=c15e065b46dc4e19837275b826c1960d55564abd <1f458fa42c29144cef280e05bc49fc21b873d897 || >=c15e065b46dc4e19837275b826c1960d55564abd <637399bf7e77797811adf340090b561a8f9d1213 | 639c70352958735addbba5ae7dd65985da96e061, 1f458fa42c29144cef280e05bc49fc21b873d897, 637399bf7e77797811adf340090b561a8f9d1213 |
| Linux/Linuxgeneric | 6.12 | Not reported |
Published upstream
Apr 1, 2025
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 5, 2026
In the Linux kernel, the following vulnerability has been resolved: net: ethtool: netlink: Allow NULL nlattrs when getting a phy_device ethnl_req_get_phydev() is used to lookup a phy_device, in the case an ethtool netlink command targets a specific phydev within a netdev's topology. It takes as a parameter a const struct nlattr *header that's used for error handling : if (!phydev) { NL_SET_ERR_MSG_ATTR(extack, header, "no phy matching phyindex"); return ERR_PTR(-ENODEV); } In the notify path after a ->set operation however, there's no request attributes available. The typical callsite for the above function looks like: phydev = ethnl_req_get_phydev(req_base, tb[ETHTOOL_A_XXX_HEADER], info->extack); So, when tb is NULL (such as in the ethnl notify path), we have a nice crash. It turns out that there's only the PLCA command that is in that case, as the other phydev-specific commands don't have a notification. This commit fixes the crash by passing the cmd index and the nlattr array separately, allowing NULL-checking it directly inside the helper.
Quoted source text, attributed separately from HOL analysis.