CVE-2026-33055

HighPublic PoC

Published: 20 March 2026

Published

20 March 2026

Modified

23 March 2026

KEV Added

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Patch

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CVSS Score 8.1 CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N

EPSS Score 0.0002 4.1th percentile

Risk Priority 16 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-33055 is a high-severity Type Confusion (CWE-843) vulnerability in Alexcrichton Tar-Rs. Its CVSS base score is 8.1 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Malicious File (T1204.002); ranked at the 4.1th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

The strongest mitigations our analysis identified are NIST 800-53 RA-5 (Vulnerability Monitoring and Scanning) and SI-2 (Flaw Remediation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Malicious File (T1204.002). What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

SI-2 Flaw Remediation good match

prevent

Directly mitigates the vulnerability by requiring timely remediation through updating tar-rs to version 0.4.45 or later, eliminating the PAX header skipping logic.

RA-5 Vulnerability Monitoring and Scanning good match

detect

Enables identification of vulnerable tar-rs versions (0.4.44 and below) through vulnerability scanning, allowing proactive patching before exploitation via malicious archives.

CM-8 System Component Inventory partial match

detect

Maintains an inventory of system components including third-party libraries like tar-rs, facilitating tracking of vulnerable versions and targeted remediation.

MITRE ATT&CK Enterprise TechniquesAI

T1204.002 Malicious File Execution

An adversary may rely upon a user opening a malicious file in order to gain execution.

attack.mitre.org →

Why these techniques?

The CVE description explicitly states exploitation requires tricking a victim into unpacking a crafted malicious tar archive (UI:R), directly mapping to user execution of a malicious file that leverages the PAX header parsing inconsistency for C/I impacts.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

tar-rs is a tar archive reading/writing library for Rust. Versions 0.4.44 and below have conditional logic that skips the PAX size header in cases where the base header size is nonzero. As part of CVE-2025-62518, the astral-tokio-tar project was changed…

to correctly honor PAX size headers in the case where it was different from the base header. This is almost the inverse of the astral-tokio-tar issue. Any discrepancy in how tar parsers honor file size can be used to create archives that appear differently when unpacked by different archivers. In this case, the tar-rs (Rust tar) crate is an outlier in checking for the header size - other tar parsers (including e.g. Go archive/tar) unconditionally use the PAX size override. This can affect anything that uses the tar crate to parse archives and expects to have a consistent view with other parsers. This issue has been fixed in version 0.4.45.

Deeper analysisAI

CVE-2026-33055 is a vulnerability in the tar-rs Rust library for reading and writing tar archives, affecting versions 0.4.44 and below. The issue arises from conditional logic that skips the PAX size header when the base header size is nonzero, making tar-rs an outlier compared to other tar parsers, such as Go's archive/tar, which unconditionally honor PAX size overrides. This leads to discrepancies where crafted tar archives unpack differently depending on the parser used, impacting any application or system relying on the tar-rs crate for consistent tar archive processing.

Attackers can exploit this vulnerability remotely with low attack complexity and no required privileges, though user interaction is necessary, such as tricking a victim into unpacking a malicious archive. Exploitation leverages the parsing inconsistency to achieve high confidentiality and integrity impacts (CVSS 8.1: AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N), potentially allowing unauthorized data access or modification in environments expecting uniform behavior across tar tools. The root cause aligns with CWE-843 (Access of Resource Using Incompatible Type).

The vulnerability has been fixed in tar-rs version 0.4.45. Official advisories recommend updating to this version or later to ensure consistent PAX header handling. Details, including the fixing commit and security advisory, are available at the tar-rs GitHub repository, with a related inverse issue documented in CVE-2025-62518.