CVE-2021-27329: Friendica 2021.01 allows SSRF via parse_url?binurl= for DNS lookups or HTTP requests to arbitrary domain names

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CRITICAL 10.0REMOTEDOWNGRADE

CVE-2021-27329 is a critical-severity flaw (CVSS 10.0) affecting frendica. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Friendica 2021.01 allows SSRF via parse_url?binurl= for DNS lookups or HTTP requests to arbitrary domain names.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	10.0 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.5% (top 25%)
CISA exploited list	No
Weakness	CWE-918
Published	2021-02-18
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: frendi

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

Am I affected?

Timeline

2021-02-18 18:15 UTCPublished CVE record published
2026-06-17 03:44 UTCUpdated Record last modified

frendi frendica DOWNGRADE

Affected: 2021.01

Fixed in: no fixed release known

Safe to downgrade to: a release before 2021.01

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2021.01 (Debian / Ubuntu)

apt-cache madison frendica sudo apt install frendica=<VERSION_BEFORE_2021.01> sudo apt-mark hold frendica

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

dnf --showduplicates list frendica sudo dnf downgrade frendica-<VERSION_BEFORE_2021.01> sudo dnf versionlock add frendica

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-2021-27329?

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

Is CVE-2021-27329 being exploited?

CVE-2021-27329 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-2021-27329 affect?

CVE-2021-27329 affects frendica. Severity is critical (CVSS 10.0). Friendica 2021.01 allows SSRF via parse_url?binurl= for DNS lookups or HTTP requests to arbitrary domain names.

How urgent is CVE-2021-27329?

Priority 64/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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