Microsoft Exchange Server 5.5 does not properly handle a MIME header with a blank charset specified, which allows remote attackers to cause
Microsoft Exchange Server 5.5 does not properly handle a MIME header with a blank charset specified, which allows remote attackers to cause a denial of service via a charset="" command, aka the "Malformed MIME Header" vulnerability.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for help- Published
- Dec 11, 2000
- Updated
- Jun 16, 2026
- EPSS
- 14.8% · 97th percentile
- CWE
- —
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Report tools
Action score
24
Monitor
Low priority for now.
- CVSS
- 20 / 40 · 5.0 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 4 / 30 · 14.8%
Affected systems
| Vendor | Product | CPE |
|---|---|---|
| microsoft | exchange server | cpe:2.3:a:microsoft:exchange_server |
Using exchange server? Add it to your stack and be the first to know about CVEs like this one. (Email server)
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- microsoft exchange server5.5
Same product
microsoft: all recordsOther highest-scoring records for the same primary product.
- CVE-2021-34523Microsoft Exchange Server Elevation of Privilege VulnerabilityKEV96Now
- CVE-2021-34473Microsoft Exchange Server Remote Code Execution VulnerabilityKEV96Now
- CVE-2021-26855Microsoft Exchange Server Remote Code Execution VulnerabilityKEV96Now
- CVE-2022-41040Microsoft Exchange Server Elevation of Privilege VulnerabilityKEV95Now
- CVE-2020-0688A remote code execution vulnerability exists in Microsoft Exchange software when the software fails to properly handle objects in memory, akKEV95Now
- CVE-2021-42321Microsoft Exchange Server Remote Code Execution VulnerabilityKEV93Now
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- none
- Integrity
- none
- Availability
- P · the service can be disrupted
- Attack complexity
- Low
- Confidentiality impact
- None
- Integrity impact
- None
- Availability impact
- P
Weakness class (CWE)
—
CVSS vector
AV:N/AC:L/Au:N/C:N/I:N/A:P
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Change log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- docs.microsoft.com/en-us/security-updates/securitybulletins/2000/ms00-082
- exchange.xforce.ibmcloud.com/vulnerabilities/5448
Vendor advisories and official records. Exploit/PoC links are deliberately left out.