Unrated

Tar entry/content smuggling in async-tar PAX extension-header parsing

IdentifiersCVE-2026-53600CWE-436

async-tar contains a flaw in handling tar PAX and related extension headers that can desynchronize parser state during archive parsing and extraction. Specifically, buffered PAX metadata records can be incorrectly applied when the current raw header is itself another extension header, including GNU longname/longlink or PAX local/global headers (L/K/x/g), rather than being reserved only for the subsequent file entry. This causes async-tar to interpret archive structure differently from POSIX-correct parsers such as GNU tar, enabling crafted tar streams to smuggle entries or content past validation and into extraction workflows.

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ANALYST BRIEF

Impact, mitigation & remediation

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Impact

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Successful exploitation can cause differential parsing and extraction behavior between async-tar and standards-compliant tar implementations. In practice, this can bypass archive scanning, validation, or policy enforcement pipelines that inspect an archive with one parser and extract it with async-tar. An attacker may hide, alter, or introduce unexpected files during extraction, including executable payloads or other malicious content that was not visible to upstream inspection logic.

Mitigation

If you can’t patch tonight, do this now.

Until patched, do not process attacker-controlled or attacker-influenced tar streams with async-tar 0.6.0 or affected main-branch code in security-sensitive workflows. Avoid architectures where one parser is used for scanning or validation and async-tar is used for extraction. If local code modification is feasible, ensure buffered PAX size/uid/gid overrides are applied only to the immediately following file entry and never to intermediary extension headers such as GNU longname/longlink or PAX local/global headers.

Remediation

Patch, then assume compromise.

Upgrade async-tar to version 0.6.1 or later. According to the advisory, the fix adds a guard preventing buffered PAX records from being applied when the current raw header is itself an extension header (L/K/x/g), eliminating the extension-header desynchronization condition.

PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

ACTIVITY FEED

Recent activity

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0 SOURCESView more in app

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