CPU exhaustion via per-byte fastForward loop
Published May 27, 2026 · Updated May 27, 2026
Inefficient algorithmic complexity in Paul Marquess IO::Uncompress::Unzip before 2.220 allows remote attackers to exhaust CPU via crafted ZIP input. fastForward compares the digit count of an entry offset with its chunk size instead of comparing the offset itself, reducing reads from 16 KiB to 1–19 bytes. Selecting a named entry from an attacker-supplied archive reaches the loop, whose work scales with compressed entry size up to 4 GiB and interrupts the calling service.
Summary
What happened
Inefficient algorithmic complexity in Paul Marquess IO::Uncompress::Unzip before 2.220 allows remote attackers to exhaust CPU via crafted ZIP input. fastForward compares the digit count of an entry offset with its chunk size instead of comparing the offset itself, reducing reads from 16 KiB to 1–19 bytes. Selecting a named entry from an attacker-supplied archive reaches the loop, whose work scales with compressed entry size up to 4 GiB and interrupts the calling service.
The record
- CVE
- CVE-2026-48959
- Published
- May 27, 2026
- Updated
- May 27, 2026
- Vendor
- Paul Marquess
- Product
- IO::Uncompress::Unzip
- Classifications
- CWE-407, T1499.004
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 27, 2026CVE publishedPublication date reported by the CVE source.
- May 27, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0 <2.220
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What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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