CVE-2023-2868
CVE-2023-2868 is a security flaw in Barracuda Networks Email Security Gateway (ESG) Appliance. Attackers can run commands on Barracuda Networks Email Security Gateway (ESG) Appliance. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 26 May 2023.[1]
Barracuda Networks Email Security Gateway (ESG) Appliance 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. Fixed in version 9.2.0.006 of Barracuda Email Security Gateway.
Description
CISA calls it an ESG appliance improper input validation in Barracuda Networks Email Security Gateway (ESG) Appliance. In its words: “Barracuda Email Security Gateway (ESG) appliance contains an improper input validation vulnerability of a user-supplied .tar file, leading to remote command injection.”[1]
The CVE record adds: “A remote command injection vulnerability exists in the Barracuda Email Security Gateway (appliance form factor only) product effecting versions 5.1.3.001-9.2.0.006. The vulnerability arises out of a failure to comprehensively sanitize the processing of .tar file (tape archives). The vulnerability stems from incomplete input validation of a user-supplied .tar file as it pertains to the names of the files contained within the archive. As a consequence, a remote attacker can specifically format these file names in a particular manner that will result in remotely executing a system command through Perl's qx operator with the privileges of the Email Security Gateway product. This issue was fixed as part of BNSF-36456 patch. This patch was automatically applied to all customer appliances.”[2]
The underlying weakness is improper input validation (CWE-20), in MITRE’s list of common software weaknesses.
It scores 9.8 out of 10 on the Common Vulnerability Scoring System, which rates it critical, scored by NVD using CVSS 3.1.[2]
Affected versions
NVD’s record lists one fixed version: everything before it is affected.[2]
| Product | Fixed in |
|---|---|
| Barracuda Email Security Gateway | 9.2.0.006 |
Most families won’t have Barracuda Networks Email Security Gateway (ESG) Appliance; it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 26 May 2023, 2 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 16 Jun 2023 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 87%. That’s in the top 1% of the flaws it scores.[4]
CISA assesses it as automatable: attackers can run it against many targets at once.
CISA doesn’t say who was attacked, or how.
Fix
Barracuda Networks has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.Barracuda Networks Email Security Gateway (ESG) Appliance 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.
- Send this page to your IT person.Ask them to confirm it’s fixed (fixed in version 9.2.0.006 of Barracuda Email Security Gateway), or not in use. CISA gave US government agencies until 16 Jun 2023 to fix it.
- 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
| Date | Event |
|---|---|
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[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 87%.[4] |
See also
Other improper input validation flaws
- CVE-2026-93952, Arista VeloCloud Orchestrator: improper input validation ·
- CVE-2019-1068, Microsoft SQL Server: remote code execution ·
- CVE-2026-12569, PTC Windchill and FlexPLM: improper input validation ·
- CVE-2026-34910, Ubiquiti UniFi OS: improper input validation ·
- CVE-2026-6973, Ivanti Endpoint Manager Mobile (EPMM): improper input validation ·
References
- ^ Cybersecurity and Infrastructure Security Agency. “Barracuda Networks ESG Appliance Improper Input Validation Vulnerability”. Known Exploited Vulnerabilities Catalog, added 26 May 2023.
- ^ National Institute of Standards and Technology. “CVE-2023-2868 Detail”. National Vulnerability Database, published 24 May 2023.
- ^ Barracuda Networks. Advisories and fixes: status.barracuda.com, barracuda.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.868, percentile 99.7, 31 Oct 2026.
- CVE Program. “CVE-2023-2868”. 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.