CVE-2021-37519: Buffer Overflow vulnerability in authfile.c memcached 1.6.9 allows attackers to cause a denial of service via

Routine

MEDIUM 5.5DOWNGRADE

CVE-2021-37519 is a medium-severity flaw (CVSS 5.5) affecting memcached. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Buffer Overflow vulnerability in authfile.c memcached 1.6.9 allows attackers to cause a denial of service via crafted authenticattion file.

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	0.4% (top 70%)
CISA exploited list	No
Weakness	CWE-787
Published	2023-02-03
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: memcached

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

Am I affected?

Timeline

2023-02-03 18:15 UTCPublished CVE record published
2026-06-17 04:00 UTCUpdated Record last modified

memcached memcached DOWNGRADE

Affected: 1.6.9

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.6.9

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.6.9 (Debian / Ubuntu)

apt-cache madison memcached sudo apt install memcached=<VERSION_BEFORE_1.6.9> sudo apt-mark hold memcached

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

dnf --showduplicates list memcached sudo dnf downgrade memcached-<VERSION_BEFORE_1.6.9> sudo dnf versionlock add memcached

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-2021-37519?

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

Is CVE-2021-37519 being exploited?

CVE-2021-37519 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-2021-37519 affect?

CVE-2021-37519 affects memcached. Severity is medium (CVSS 5.5). Buffer Overflow vulnerability in authfile.c memcached 1.6.9 allows attackers to cause a denial of service via crafted authenticattion file.

How urgent is CVE-2021-37519?

Priority 32/100. Public exploit reference

Software pages

Memcached vulnerabilities

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References

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