VulnerabilityPublished 20 Mar 2026

CVE-2026-33055: alexcrichton tar-rs · Type Confusion

Affects alexcrichton tar-rsSource CVE Database V5

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Mentioned vulnerabilities

CVE-2025-62518

Not known to be exploited · CVSS 5.1 Medium : upgrade to 0.4.45 when convenient.

Data as of 31 Oct 2026, 20:20 UTC

CVSS 4.0 base score

5.1Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 35% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 0.4.45

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Attack Vector: Network
Attack Complexity: Low
Attack Requirements: None
Privileges Required: None
User Interaction: Active
Vulnerable system confidentiality: Low
Vulnerable system integrity: Low
Vulnerable system availability: None
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction: Active: Successful exploitation of this vulnerability requires a targeted user to perform specific, conscious interactions with the vulnerable system and the attacker’s payload, or the user’s interactions would actively subvert protection mechanisms which would lead to exploitation of the vulnerability.
Vulnerable system confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to the Vulnerable System.
Vulnerable system availability: None: There is no impact to availability within the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 20 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 31 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade tar-rs and alexcrichton/tar-rs to 0.4.45.

Affected software

Product	Affected	Fixed in
alexcrichtontar-rs	Affected <0.4.45	Fixed in 0.4.45
crates.ioalexcrichton/tar-rs`pkg:cargo/alexcrichton/tar-rs`Other threats	Affected <0.4.45	Fixed in 0.4.45

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

The definitive mitigation is to upgrade all instances of the tar-rs crate to version 0.4.45 or later, where the handling of PAX size headers is corrected. Developers should audit their Rust dependencies to identify usage of tar-rs and ensure timely updates. Additionally, organizations should implement strict validation and sanitization of tar archives before processing, including verifying archive consistency across multiple parsers if feasible. Employing sandboxing or running archive extraction in isolated environments can limit potential damage from malformed archives. Monitoring for unusual archive unpacking behaviors or discrepancies in file sizes can help detect exploitation attempts. Finally, educating developers and DevOps teams about this inconsistency will reduce the risk of integrating vulnerable versions into production systems.

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.

Impact

The primary impact of this vulnerability is on the integrity and consistency of archive unpacking processes in applications using tar-rs. Discrepancies in file size interpretation can lead to unexpected behavior such as overwriting files, bypassing security controls that rely on archive content validation, or causing application logic errors. This can affect software supply chains, automated deployment pipelines, or any Rust-based systems that consume tar archives. While it does not directly lead to remote code execution or privilege escalation, the inconsistency can be leveraged in complex attack scenarios involving crafted archives to disrupt operations or evade detection. Organizations relying on tar-rs for critical archive processing may experience data integrity issues or operational disruptions. Since no known exploits are reported, the immediate risk is moderate, but the potential for misuse exists especially in environments where archive integrity is critical.

Summary

CVE-2026-33055 is a vulnerability in the tar-rs Rust crate, a library for reading and writing tar archives. The flaw stems from conditional logic in versions 0.4.44 and earlier that skips processing the PAX size header when the base header size is nonzero. This contrasts with other tar parsers, such as Go's archive/tar, which always honor the PAX size override unconditionally. The inconsistency leads to a type confusion scenario (CWE-843) where archives crafted with differing size headers can be interpreted differently by tar-rs compared to other parsers. This discrepancy can cause files to appear with different sizes or contents depending on the parser used, potentially enabling attackers to craft malicious archives that behave unexpectedly or bypass security checks relying on consistent archive parsing. The vulnerability does not involve direct memory corruption but impacts the integrity and reliability of archive unpacking. It requires user interaction to unpack a malicious archive but no privileges or authentication. The issue was addressed in tar-rs version 0.4.45 by aligning the handling of PAX size headers with other parsers, ensuring consistent interpretation of archive contents.

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 20 Mar 2026, 07:39 UTC

WeaknessesCWE-843

Technical details

References

Community reviews

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