CVE-2021-26476: EPrints 3.4.2 allows remote attackers to execute OS commands via crafted LaTeX input to a cgi/cal?year= URI.

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2021-26476 is a critical-severity flaw (CVSS 9.8) affecting eprints. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

EPrints 3.4.2 allows remote attackers to execute OS commands via crafted LaTeX input to a cgi/cal?year= URI.

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	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.1% (top 12%)
CISA exploited list	No
Weakness	CWE-78
Published	2021-03-01
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: eprints

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

Am I affected?

Timeline

2021-03-01 22:15 UTCPublished CVE record published
2026-06-17 03:43 UTCUpdated Record last modified

eprints eprints DOWNGRADE

Affected: 3.4.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.4.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.4.2 (Debian / Ubuntu)

apt-cache madison eprints sudo apt install eprints=<VERSION_BEFORE_3.4.2> sudo apt-mark hold eprints

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

dnf --showduplicates list eprints sudo dnf downgrade eprints-<VERSION_BEFORE_3.4.2> sudo dnf versionlock add eprints

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-2021-26476?

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

Is CVE-2021-26476 being exploited?

CVE-2021-26476 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-2021-26476 affect?

CVE-2021-26476 affects eprints. Severity is critical (CVSS 9.8). EPrints 3.4.2 allows remote attackers to execute OS commands via crafted LaTeX input to a cgi/cal?year= URI.

How urgent is CVE-2021-26476?

Priority 66/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2021-3342 CRITICAL 9.8 DOWNGRADE EPrints 3.4.2 allows remote attackers to read arbitrary files and possibly execute commands via crafted LaTeX
CVE-2021-26704 HIGH 8.8 DOWNGRADE EPrints 3.4.2 allows remote attackers to execute arbitrary commands via crafted input to the verb parameter in
CVE-2021-26703 CRITICAL 9.8 DOWNGRADE EPrints 3.4.2 allows remote attackers to read arbitrary files and possibly execute commands via crafted JSON/X
CVE-2021-26702 MEDIUM 6.1 DOWNGRADE EPrints 3.4.2 exposes a reflected XSS opportunity in the dataset parameter to the cgi/dataset_dictionary URI.
CVE-2021-26475 MEDIUM 6.1 DOWNGRADE EPrints 3.4.2 exposes a reflected XSS opportunity in the via a cgi/cal URI.

References

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