CVE-2026-89743 (CVSS 7.7)

Description

In the Linux kernel, the following vulnerability has been resolved: misc: nsm: bound the device-reported response length nsm_sendrecv_msg_locked() stores the virtqueue used-ring length reported by the NSM device into msg->resp.len without bounding it to the response buffer. A malicious or buggy backend can report a length larger than the response buffer; parse_resp_raw() then copies that many bytes out of the fixed buffer to user space, disclosing adjacent kernel heap (an out-of-bounds read). The request path already floors its length in fill_req_raw(); the response path lacks the symmetric check. Clamp the stored length to the size of the response buffer. Well-behaved devices report no more than the posted buffer size, so conforming traffic is unaffected.

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CVSS v3.1 Score

7.7

HIGH

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

EPSS — Exploit Prediction

0.0014

Probability of exploitation

0.04%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

References

Other References

https://git.kernel.org/stable/c/29e634a18957acda11383a15ab98a91c4ae9e294 https://git.kernel.org/stable/c/2aa0fb9c96f894a9c179a48e7522ea6705800adf https://git.kernel.org/stable/c/339f19b9a6171289b0e797deb8bda80b9a1fcc30 https://git.kernel.org/stable/c/808e530654a5354e6df78863a5d61e4d44e67235

Frequently Asked Questions

What is CVE-2026-89743? +

In the Linux kernel, the following vulnerability has been resolved: misc: nsm: bound the device-reported response length nsm_sendrecv_msg_locked() stores the virtqueue used-ring length reported by the NSM device into msg->resp.len without bounding it to the response buffer. A malicious or buggy backend can report a length larger than the response buffer; parse_resp_raw() then copies that many bytes out of the fixed buffer to user space, disclosing adjacent kernel heap (an out-of-bounds read). The request path already floors its length in fill_req_raw(); the response path lacks the symmetric check. Clamp the stored length to the size of the response buffer. Well-behaved devices report no more than the posted buffer size, so conforming traffic is unaffected. It has a CVSS v3.1 base score of 7.7 (HIGH).

How severe is CVE-2026-89743? +

CVE-2026-89743 has a CVSS v3.1 score of 7.7 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0014, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-89743? +

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.

CVE-2026-89743