CVE-2022-37042
CVE-2022-37042 is a security flaw in Synacor Zimbra Collaboration Suite (ZCS), email and calendar software companies run on their own servers. Attackers can run their own code on Synacor Zimbra Collaboration Suite (ZCS) from anywhere, without logging in. The US Cybersecurity and Infrastructure Security Agency (CISA) added it to its catalog of flaws known to be used in attacks on 11 Aug 2022, and says ransomware gangs have used it.[1]
Synacor Zimbra Collaboration Suite (ZCS) 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. Synacor has published a fix or advice.
Description
CISA calls it an authentication bypass in Synacor Zimbra Collaboration Suite (ZCS). In its words: “Synacor Zimbra Collaboration Suite (ZCS) contains an authentication bypass vulnerability in MailboxImportServlet. This vulnerability was chained with CVE-2022-27925 which allows for unauthenticated remote code execution.”[1]
The CVE record adds: “Zimbra Collaboration Suite (ZCS) 8.8.15 and 9.0 has mboximport functionality that receives a ZIP archive and extracts files from it. By bypassing authentication (i.e., not having an authtoken), an attacker can upload arbitrary files to the system, leading to directory traversal and remote code execution. NOTE: this issue exists because of an incomplete fix for CVE-2022-27925.”[2]
The underlying weakness is CWE-23, 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 doesn’t list version ranges for it; Synacor’s advisory has them[3]. CISA names the product as Synacor Zimbra Collaboration Suite (ZCS).
Most families won’t have Synacor Zimbra Collaboration Suite (ZCS); it’s for whoever looks after IT at work.
Exploitation
CISA added it to its catalog of known exploited vulnerabilities on 11 Aug 2022. CISA lists a flaw only when it has reliable evidence of it being exploited, and gave US federal agencies until 1 Sep 2022 to fix it.[1] CISA says ransomware gangs have used it.
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 92%. 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
Synacor has published a fix or advice.[3] CISA’s required action: “Apply updates per vendor instructions.”[1]
- Check whether you use it.Synacor Zimbra Collaboration Suite (ZCS) 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, or not in use. CISA gave US government agencies until 1 Sep 2022 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 |
|---|---|
| CISA adds it to its catalog of flaws known to be used in attacks, noting that ransomware gangs have used it.[1] | |
| The flaw is made public in the National Vulnerability Database, with a severity score of 9.8.[2] | |
| 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 92%.[4] |
See also
Other Synacor Zimbra Collaboration Suite (ZCS) flaws
- CVE-2026-73570: OS command injection ·
- CVE-2025-48700: cross-site scripting ·
- CVE-2025-66376: cross-site scripting ·
- CVE-2025-68645: PHP remote file inclusion ·
- CVE-2025-27915: cross-site scripting ·
- CVE-2019-9621: server-side request forgery (SSRF) ·
Other Synacor flaws
- CVE-2020-7796, Synacor Zimbra Collaboration Suite: (ZCS) server-side request forgery ·
- CVE-2022-24682, Synacor Zimbra Collaborate Suite (ZCS): cross-site scripting ·
Similar flaws
- CVE-2026-76519, Cisco Secure Email Gateway: relative path traversal ·
- CVE-2026-34926, Trend Micro Apex One: (on-premise) directory traversal ·
- CVE-2024-27199, JetBrains TeamCity: relative path traversal ·
- CVE-2025-64446, Fortinet FortiWeb: path traversal ·
- CVE-2021-38163, SAP NetWeaver: unrestricted file upload ·
Added the same day
- CVE-2022-27925, Synacor Zimbra Collaboration Suite (ZCS): arbitrary file upload ·
Every Synacor flaw on CISA’s list · Everything added in August 2022
References
- ^ Cybersecurity and Infrastructure Security Agency. “Synacor Zimbra Collaboration Suite (ZCS) Authentication Bypass Vulnerability”. Known Exploited Vulnerabilities Catalog, added 11 Aug 2022.
- ^ National Institute of Standards and Technology. “CVE-2022-37042 Detail”. National Vulnerability Database, published 12 Aug 2022.
- ^ Synacor. Advisories and fixes: blog.zimbra.com, wiki.zimbra.com, wiki.zimbra.com.
- ^ FIRST. “Exploit Prediction Scoring System”. EPSS 0.921, percentile 99.8, 31 Oct 2026.
- CVE Program. “CVE-2022-37042”. 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.