CVE-2018-6654: The Grammarly extension before 2018-02-02 for Chrome allows remote attackers to discover authentication tokens

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HIGH 8.8DOWNGRADE

CVE-2018-6654 is a high-severity flaw (CVSS 8.8) affecting grammarly. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The Grammarly extension before 2018-02-02 for Chrome allows remote attackers to discover authentication tokens via an 'action: "user"' request to iframe.gr_-ifr, because the exposure of these tokens is not restricted to any specific web site.

Why this priority

High severity
Public exploit reference

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

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.5% (top 57%)
CISA exploited list	No
Weakness	CWE-346
Published	2018-02-06
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: grammarly

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

Am I affected?

Timeline

2018-02-06 01:29 UTCPublished CVE record published
2026-06-17 02:02 UTCUpdated Record last modified

grammarly grammarly DOWNGRADE

Affected: 2018-02-02

Fixed in: no fixed release known

Safe to downgrade to: a release before 2018-02-02

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2018-02-02 (Debian / Ubuntu)

apt-cache madison grammarly sudo apt install grammarly=<VERSION_BEFORE_2018-02-02> sudo apt-mark hold grammarly

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

dnf --showduplicates list grammarly sudo dnf downgrade grammarly-<VERSION_BEFORE_2018-02-02> sudo dnf versionlock add grammarly

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-2018-6654?

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

Is CVE-2018-6654 being exploited?

CVE-2018-6654 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-2018-6654 affect?

CVE-2018-6654 affects grammarly. Severity is high (CVSS 8.8). The Grammarly extension before 2018-02-02 for Chrome allows remote attackers to discover authentication tokens via an 'action: "user"' request to iframe.gr_-ifr, because the exposure of these tokens is not restricted to any specific web sit

How urgent is CVE-2018-6654?

Priority 47/100. High severity; Public exploit reference

Software pages

Google Chrome vulnerabilities

References

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