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CVE-2021-22204

From Exploited flaws, HARD’s guide to the flaws being used in attacks · Checked
This article is about a flaw in Perl Exiftool. For every flaw being used in attacks, see Exploited flaws.

CVE-2021-22204 is a security flaw in Perl Exiftool. Attackers can run their own code on Perl Exiftool. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 17 Nov 2021.[1]

Perl Exiftool is business software or equipment. Most families won’t have it, but attackers break into it to get inside companies, and from there to what those companies hold about their customers, patients and staff. Perl has published a fix or advice.

Description

CISA calls it a remote code execution in Perl Exiftool. In its words: “Improper neutralization of user data in the DjVu file format in Exiftool versions 7.44 and up allows arbitrary code execution when parsing the malicious image”[1]

The underlying weakness is CWE-95, in MITRE’s list of common software weaknesses.[2]

It scores 7.8 out of 10 on the Common Vulnerability Scoring System, which rates it high, scored by NVD using CVSS 3.1.[2]

Affected versions

NVD’s record doesn’t list version ranges for it; Perl’s advisory has them[3]. CISA names the product as Perl Exiftool.

Most families won’t have Perl Exiftool; it’s for whoever looks after IT at work.

Exploitation

CISA added it to its catalog of known exploited vulnerabilities on 17 Nov 2021, 208 days after it was made public. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 1 Dec 2021 to fix it.[1]

FIRST’s Exploit Prediction Scoring System, which estimates how likely a flaw is to be used in attacks in the next 30 days from what it sees across the internet, puts it at over 99%. That’s in the top 1% of the flaws it scores.[4]

CISA assesses it as not automatable: each attack takes some work.

CISA doesn’t say who was attacked, or how.

Fix

Perl has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]

  1. Check whether you use it.Perl Exiftool is business software or equipment, so most families won’t have it. If you run a business, or work from home on company equipment, ask whoever looks after your IT.
  2. Send this page to your IT person.Ask them to confirm it’s fixed, or not in use. CISA gave US government agencies until 1 Dec 2021 to fix it.
  3. If it can’t be fixed, take it offline.CISA’s advice when there’s no fix is to stop using the product, or take it off the internet, until there is one.

You can’t fix someone else’s server, but you can watch for what follows a break-in like this: a breach notice, a password reset you didn’t ask for, or a scam message that knows things it shouldn’t. HARD watches for those for you and your family.

Timeline

DateEvent
The flaw is made public in the National Vulnerability Database, with a severity score of 7.8.[2]
CISA adds it to its catalog of flaws known to be used in attacks.[1]
CISA’s deadline for US government agencies to fix it.[1]
FIRST puts the odds of it being used in attacks in the next 30 days at over 99%.[4]

See also

Similar flaws

  • CVE-2025-24893, XWiki Platform: eval injection ·
  • CVE-2024-36401, OSGeo GeoServer: geoTools eval injection ·
  • CVE-2023-7101, Spreadsheet::ParseExcel: remote code execution ·

Added the same day

  • CVE-2021-42321, Microsoft Exchange: server remote code execution ·
  • CVE-2021-42292, Microsoft Office: excel security feature bypass ·
  • CVE-2021-40449, Microsoft Windows: win32k privilege escalation ·

References

  1. ^ Cybersecurity and Infrastructure Security Agency. “ExifTool Remote Code Execution Vulnerability”. Known Exploited Vulnerabilities Catalog, added 17 Nov 2021.
  2. ^ National Institute of Standards and Technology. “CVE-2021-22204 Detail”. National Vulnerability Database, published 23 Apr 2021.
  3. ^ Perl. Advisories and fixes: lists.fedoraproject.org, lists.fedoraproject.org, lists.fedoraproject.org.
  4. ^ FIRST. “Exploit Prediction Scoring System”. EPSS 1.000, percentile 100.0, 31 Oct 2026.
  5. CVE Program. “CVE-2021-22204”. The official CVE record.

This article is built from CISA’s catalog (version 2026.10.30), NVD’s record and FIRST’s scores, kept in HARD’s database and checked every morning. The plain English is HARD’s.