CVE-2019-15847 — The POWER9 backend in GNU Compiler Collection (GCC) before version 10 could opti

The POWER9 backend in GNU Compiler Collection (GCC) before version 10 could optimize multiple calls of the __builtin_darn intrinsic into a single call, thus reducing the entropy of the random number generator. This occurred because a volatile operation was not specified. For exam

01What is this vulnerability?

The POWER9 backend in GNU Compiler Collection (GCC) before version 10 could optimize multiple calls of the __builtin_darn intrinsic into a single call, thus reducing the entropy of the random number generator. This occurred because a volatile operation was not specified. For example, within a single execution of a program, the output of every __builtin_darn() call may be the same.

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: 2019-09-02T23:15:10.837
• Last modified: 2026-10-14T07:16:46.907

09References

• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00056.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00057.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00058.html
• gcc.gnu.org — https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91481
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00056.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00057.html
• lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00058.html
• gcc.gnu.org — https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91481
• cert-portal.siemens.com — https://cert-portal.siemens.com/productcert/html/ssa-398330.html