Heap overflow via unchecked iconv writes
Published Aug 19, 2026 · Updated Aug 19, 2026
Heap overflow in iconv(3) in FreeBSD allows attackers to corrupt process memory via crafted HZ, UTF-7, VIQR, or ZW text. Several iconv encoding modules write converted characters into a caller-supplied output buffer without first confirming sufficient space, and the FreeBSD HZ fix enlarges internal state storage because wcrtomb can emit two 2-byte escape sequences in addition to the character itself. Exposure requires a reachable application that passes attacker-controlled text through the affected encodings on FreeBSD before 14.3-RELEASE-p16, 14.4-RELEASE-p7, 15.0-RELEASE-p11, or 15.1-RELEASE-p1; the advisory confirms heap memory corruption but does not further characterize code-execution reachability.
Summary
What happened
Heap overflow in iconv(3) in FreeBSD allows attackers to corrupt process memory via crafted HZ, UTF-7, VIQR, or ZW text. Several iconv encoding modules write converted characters into a caller-supplied output buffer without first confirming sufficient space, and the FreeBSD HZ fix enlarges internal state storage because wcrtomb can emit two 2-byte escape sequences in addition to the character itself. Exposure requires a reachable application that passes attacker-controlled text through the affected encodings on FreeBSD before 14.3-RELEASE-p16, 14.4-RELEASE-p7, 15.0-RELEASE-p11, or 15.1-RELEASE-p1; the advisory confirms heap memory corruption but does not further characterize code-execution reachability.
The record
- CVE
- CVE-2026-58081
- Published
- Aug 19, 2026
- Updated
- Aug 19, 2026
- Vendor
- The FreeBSD Project
- Product
- FreeBSD
- Classifications
- CWE-122
- Attack vector
- Unavailable
- Privileges
- Unavailable
Timeline
How it unfolded
- Aug 19, 2026CVE publishedPublication date reported by the CVE source.
- Aug 19, 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?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=14.3-RELEASE <p16
- Affected versionversion=14.4-RELEASE <p7
- Affected versionversion=15.0-RELEASE <p11
- Affected versionversion=15.1-RELEASE <p1
What conditions does exploitation require?
What is affected?
Published CVSS scores
No CVSS assessment is available in this record.
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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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