Inefficient complexity in the Sieve filter evaluation of Progressive Robot hMailServer 6.2.24 through 6.3.5 allows an authenticated account holder to make the mail services unavailable with their own filter. A ':matches' pattern was matched by a backtracking descent whose time grew with the matched value's length raised to the number of wildcards, so a pattern such as '*a*a*a*b' over 800 characters took 44 seconds; and 'deleteheader' erased the fields it removed one at a time, so removing many fields of one name over a message's header cost O(N^2) (80,000 fields took 18.8 seconds). Sieve filters run on the small, shared delivery thread pool, so an account holder whose active script does this, fed a few messages they can send themselves, empties the pool and stops delivery for the whole server. The script is the account holder's own and cannot be set for another user.
Metrics
Affected Vendors & Products
References
History
Thu, 08 Oct 2026 18:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Thu, 08 Oct 2026 13:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Progressive Robot
Progressive Robot hmailserver |
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| Vendors & Products |
Progressive Robot
Progressive Robot hmailserver |
Thu, 08 Oct 2026 12:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | Inefficient complexity in the Sieve filter evaluation of Progressive Robot hMailServer 6.2.24 through 6.3.5 allows an authenticated account holder to make the mail services unavailable with their own filter. A ':matches' pattern was matched by a backtracking descent whose time grew with the matched value's length raised to the number of wildcards, so a pattern such as '*a*a*a*b' over 800 characters took 44 seconds; and 'deleteheader' erased the fields it removed one at a time, so removing many fields of one name over a message's header cost O(N^2) (80,000 fields took 18.8 seconds). Sieve filters run on the small, shared delivery thread pool, so an account holder whose active script does this, fed a few messages they can send themselves, empties the pool and stops delivery for the whole server. The script is the account holder's own and cannot be set for another user. | |
| Title | Inefficient Regular Expression Complexity in hMailServer | |
| Weaknesses | CWE-1333 | |
| References |
| |
| Metrics |
cvssV3_1
|
Status: PUBLISHED
Assigner: GitLab
Published: 2026-10-08T11:46:41.080Z
Updated: 2026-10-08T17:35:21.719Z
Reserved: 2026-10-08T10:51:25.637Z
Link: CVE-2026-107572
Updated: 2026-10-08T17:35:14.413Z
Status : Deferred
Published: 2026-10-08T12:17:14.870
Modified: 2026-10-08T21:02:43.860
Link: CVE-2026-107572
No data.