HIGH
CVE-2021-28994
CWE-770Published: March 31, 2021· Updated: Jun 17, 2026
7.5
CVSS v3.1
Official Description
kopano-ical (formerly zarafa-ical) in Kopano Groupware Core through 8.7.16, 9.x through 9.1.0, 10.x through 10.0.7, and 11.x through 11.0.1 and Zarafa 6.30.x through 7.2.x allows memory exhaustion via long HTTP headers.
Technical Analysis
CVE-2021-28994 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.
The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.
A successful exploit results in availability disruption (denial of service), with a CVSS base score of 7.5.
CVSS v3.1 Vector Breakdown
Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityNone
AvailabilityHigh
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected Vendors & Products
Exploit & PoC Resources
NO KNOWN EXPLOITNo public exploit confirmed at this time
Exploit-DB
Offensive Security exploit database
GitHub PoC Search
Community PoC repositories
Rapid7 / Metasploit
Metasploit module search
PacketStorm
Security advisories & exploits
NVD Detail
Official NIST entry
MITRE CVE
CVE Program entry
External links open in a new tab. Always verify in a controlled environment before use.
Official Patches & Advisories
All References (6)
→
http://www.openwall.com/lists/oss-security/2021/04/01/1Mailing List · Third Party Advisory
→
http://www.openwall.com/lists/oss-security/2021/04/25/1Mailing List · Third Party Advisory
→
https://www.openwall.com/lists/oss-security/2021/03/19/6Exploit · Mailing List · Third Party Advisory
→
http://www.openwall.com/lists/oss-security/2021/04/01/1Mailing List · Third Party Advisory
→
http://www.openwall.com/lists/oss-security/2021/04/25/1Mailing List · Third Party Advisory
→
https://www.openwall.com/lists/oss-security/2021/03/19/6Exploit · Mailing List · Third Party Advisory
Quick Facts
CVE IDCVE-2021-28994
CVSS Score7.5 / 10
SeverityHIGH
WeaknessCWE-770
CISA KEVNo
Affected2 vendor(s)
PublishedMar 31, 2021
Related CVEs (CWE-770)
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-28994 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWatch. CVE data is provided under the NVD usage policy.