CVE-2021-45935: Grok 9.5.0 has a heap-based buffer overflow in openhtj2k::T1OpenHTJ2K::decompress (called from std::1::pac

Q: How urgent is CVE-2021-45935?

Priority 39/100. Public exploit reference

Routine

MEDIUM 5.5DOWNGRADE

CVE-2021-45935 is a medium-severity flaw (CVSS 5.5) affecting grok. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Grok 9.5.0 has a heap-based buffer overflow in openhtj2k::T1OpenHTJ2K::decompress (called from std::__1::__packaged_task_func<std::__1::__bind<grk::T1DecompressScheduler::deco and std::__1::packaged_task<int).

Why this priority

Public exploit reference

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

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.9% (top 40%)
CISA exploited list	No
Weakness	CWE-787
Published	2022-01-01
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: grok project

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

Am I affected?

Timeline

2022-01-01 01:15 UTCPublished CVE record published
2026-06-17 04:14 UTCUpdated Record last modified

grok project grok DOWNGRADE

Affected: 9.5.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.5.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 9.5.0 (Debian / Ubuntu)

apt-cache madison grok sudo apt install grok=<VERSION_BEFORE_9.5.0> sudo apt-mark hold grok

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

dnf --showduplicates list grok sudo dnf downgrade grok-<VERSION_BEFORE_9.5.0> sudo dnf versionlock add grok

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-2021-45935?

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

Is CVE-2021-45935 being exploited?

CVE-2021-45935 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-2021-45935 affect?

CVE-2021-45935 affects grok. Severity is medium (CVSS 5.5). Grok 9.5.0 has a heap-based buffer overflow in openhtj2k::T1OpenHTJ2K::decompress (called from std::__1::__packaged_task_func<std::__1::__bind<grk::T1DecompressScheduler::deco and std::__1::packaged_task<int).

How urgent is CVE-2021-45935?