Heap overflow via wrapped zisofs allocation
Published Mar 30, 2026 · Updated Mar 30, 2026
Heap buffer overflow in libarchive on 32-bit Red Hat systems allows remote attackers to overwrite heap memory via a crafted ISO9660 image. zisofs_read_data computes a block-pointer allocation from an unchecked Rock Ridge ZF block-size exponent; on 32-bit builds the size wraps to zero before attacker-controlled data is copied into the tiny allocation. Reachability requires a 32-bit process and an application that reads or extracts the image; code execution additionally requires platform-specific heap grooming.
Summary
What happened
Heap buffer overflow in libarchive on 32-bit Red Hat systems allows remote attackers to overwrite heap memory via a crafted ISO9660 image. zisofs_read_data computes a block-pointer allocation from an unchecked Rock Ridge ZF block-size exponent; on 32-bit builds the size wraps to zero before attacker-controlled data is copied into the tiny allocation. Reachability requires a 32-bit process and an application that reads or extracts the image; code execution additionally requires platform-specific heap grooming.
The record
- CVE
- CVE-2026-5121
- Published
- Mar 30, 2026
- Updated
- Mar 30, 2026
- Vendor
- 389 Directory Server
- Product
- Red Hat Enterprise Linux 10
- Classifications
- CWE-190
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 30, 2026CVE publishedPublication date reported by the CVE source.
- Mar 30, 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?
Affected versions are unavailable in this record. Check the vendor advisory for version and patch details.
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Upstream crafted ISO9660 regression artifactproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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