CVE-2017-17806 — The HMAC implementation (crypto/hmac

The HMAC implementation (crypto/hmac.c) in the Linux kernel before 4.14.8 does not validate that the underlying cryptographic hash algorithm is unkeyed, allowing a local attacker able to use the AF_ALG-based hash interface (CONFIG_CRYPTO_USER_API_HASH) and the SHA-3 hash algorith

01What is this vulnerability?

The HMAC implementation (crypto/hmac.c) in the Linux kernel before 4.14.8 does not validate that the underlying cryptographic hash algorithm is unkeyed, allowing a local attacker able to use the AF_ALG-based hash interface (CONFIG_CRYPTO_USER_API_HASH) and the SHA-3 hash algorithm (CONFIG_CRYPTO_SHA3) to cause a kernel stack buffer overflow by executing a crafted sequence of system calls that…

02Affected products

No structured affected-product list available — see references below for vendor advisories.

03Active exploitation status

Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.

04Recommended remediation

• Patch to a fixed version listed in the vendor advisory (see references below).
• Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
• Hunt historical logs for exploitation indicators — see Detection signatures below.

05Technical details

For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.

06Detection signatures

Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.

07Related CVEs

No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.

08Timeline

• Published: 2017-12-20T23:29:00.377
• Last modified: 2026-05-13T00:24:29.033

09References

• git.kernel.org — http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=af3ff8…
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2018-01/msg00006.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2018-01/msg00007.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2018-01/msg00008.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2018-01/msg00014.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2018-01/msg00016.html
• www.securityfocus.com — http://www.securityfocus.com/bid/102293
• access.redhat.com — https://access.redhat.com/errata/RHSA-2018:2948
• github.com — https://github.com/torvalds/linux/commit/af3ff8045bbf3e32f1a448542e73abb4c8ceb6f…
• lists.debian.org — https://lists.debian.org/debian-lts-announce/2018/01/msg00004.html