CVE-2020-22284: A buffer overflow vulnerability in the zepif_linkoutput() function of Free Software Foundation lwIP git head v

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HIGH 7.5REMOTEDOWNGRADE

CVE-2020-22284 is a high-severity flaw (CVSS 7.5) affecting lwip. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A buffer overflow vulnerability in the zepif_linkoutput() function of Free Software Foundation lwIP git head version and version 2.1.2 allows attackers to access sensitive information via a crafted 6LoWPAN packet.

Why this priority

High severity
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.2% (top 32%)
CISA exploited list	No
Weakness	CWE-120
Published	2021-07-22
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: lwip project

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

Am I affected?

Timeline

2021-07-22 20:15 UTCPublished CVE record published
2026-06-17 03:04 UTCUpdated Record last modified

lwip project lwip DOWNGRADE

Affected: 2.1.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.1.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.1.2 (Debian / Ubuntu)

apt-cache madison lwip sudo apt install lwip=<VERSION_BEFORE_2.1.2> sudo apt-mark hold lwip

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

dnf --showduplicates list lwip sudo dnf downgrade lwip-<VERSION_BEFORE_2.1.2> sudo dnf versionlock add lwip

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-2020-22284?

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

Is CVE-2020-22284 being exploited?

CVE-2020-22284 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-2020-22284 affect?

CVE-2020-22284 affects lwip. Severity is high (CVSS 7.5). A buffer overflow vulnerability in the zepif_linkoutput() function of Free Software Foundation lwIP git head version and version 2.1.2 allows attackers to access sensitive information via a crafted 6LoWPAN packet.

How urgent is CVE-2020-22284?

Priority 48/100. High severity; Remotely exploitable, no login, no user action

Software pages

Git vulnerabilities

Related CVEs

CVE-2020-22283 HIGH 7.5 MITIGATE A buffer overflow vulnerability in the icmp6_send_response_with_addrs_and_netif() function of Free Software Fo

References

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