CVE-2017-11671: Under certain circumstances, the ix86_expand_builtin function in i386.c in GNU Compiler Collection (GCC) versi

Routine

MEDIUM 4.0DOWNGRADE

CVE-2017-11671 is a medium-severity flaw (CVSS 4.0) affecting gcc. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Under certain circumstances, the ix86_expand_builtin function in i386.c in GNU Compiler Collection (GCC) version 4.6, 4.7, 4.8, 4.9, 5 before 5.5, and 6 before 6.4 will generate instruction sequences that clobber the status flag of the RDRAND and RDSEED intrinsics before it can be read, potentially causing failures of these instructions to go unreported. This could potentially lead to less randomness in random number generation.

Why this priority

No elevated risk signals yet

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	4.0 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-338
Published	2017-07-26
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: gnu

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2017-07-26 21:29 UTCPublished CVE record published
2026-06-17 01:02 UTCUpdated Record last modified

gnu gcc DOWNGRADE

Affected: 4.6 · 4.7 · 4.8 · 4.9 · 5.0 · 5.1 · 5.2 · 5.3

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.6

1. Check installed version

apt-cache policy gcc || rpm -q gcc || gcc --version

2. No fixed release: DOWNGRADE to a release before 4.6 (Debian / Ubuntu)

apt-cache madison gcc sudo apt install gcc=<VERSION_BEFORE_4.6> sudo apt-mark hold gcc

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list gcc sudo dnf downgrade gcc-<VERSION_BEFORE_4.6> sudo dnf versionlock add gcc

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2017-11671?

gcc: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-11671 being exploited?

CVE-2017-11671 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2017-11671 affect?

CVE-2017-11671 affects gcc. Severity is medium (CVSS 4.0). Under certain circumstances, the ix86_expand_builtin function in i386.c in GNU Compiler Collection (GCC) version 4.6, 4.7, 4.8, 4.9, 5 before 5.5, and 6 before 6.4 will generate instruction sequences that clobber the status flag of the RDRA

How urgent is CVE-2017-11671?

Priority 24/100. No elevated risk signals yet.

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References

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