GHSA-v23m-ccfg-pq9h CVE-2026-55700

pnpm: `stage download` writes outside its destination directory via manifest name/version traversal

High npm

Severity: 7.1 / 10; High · CVSS 3.1
Exploit chance (EPSS): 0.42%; Chance of exploitation in the next 30 days. Higher than 36.05% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'); CWE-73 External Control of File Name or Path
Fix: 11.5.3; Upgrade pnpm to this version or later

Description

Summary

The staged-tarball filename traversal reported as GHSA-v23m-ccfg-pq9h / CAND-PNPM-038 is fixed on main by pnpm/pnpm#12303, merged as 65443f4bdf1f0db9c8c7dc58fee25252607e9234.

Before the fix, pnpm stage download derived a local filename from registry-controlled package name and version fields. A crafted manifest could escape the selected download directory and overwrite another reachable file. The merged fix validates both fields, derives one safe filename, and verifies the final destination before writing.

Security boundary

Package names and semantic versions are validated before they can influence a local filename.
POSIX and Windows path separators are rejected by basename checks.
Stage download and tarball summary paths use the same filename helper.
The resolved output path must remain an immediate child of the selected download directory.
The stage identifier is already constrained to a UUID.

Exploit replay

Before 65443f4bdf, a traversal-bearing manifest version could make the command write outside the selected directory. After the fix, malicious package names fail with ERR_PNPM_INVALID_PACKAGE_NAME, malicious versions fail with ERR_PNPM_INVALID_PACKAGE_VERSION, no outside file is created, and the download directory remains empty.

Files changed

releasing/commands/src/tarball/safeTarballFilename.ts validates manifest identity and rejects cross-platform path separators.
releasing/commands/src/stage/download.ts verifies the resolved destination before writing.
releasing/commands/src/tarball/summarizeTarball.ts uses the same filename contract.
releasing/commands/test/stage.test.ts covers traversal through both package name and version.
.changeset/stale-stage-tarballs.md includes patch bumps for @pnpm/releasing.commands and pnpm.

Patch

Merged PR: https://github.com/pnpm/pnpm/pull/12303
Fix commit: 65443f4bdf1f0db9c8c7dc58fee25252607e9234
The private candidate branch was not submitted because it conflicts with and is superseded by the merged fix. The upstream patch is slightly stronger because it covers malicious package names as well as versions.

Commands run

$ git diff --check 65443f4bdf^ 65443f4bdf
PASS
$ gh pr view 12303 --repo pnpm/pnpm --json state,mergeCommit,statusCheckRollup
MERGED as 65443f4bdf

Validation

Upstream regression coverage rejects traversal through both manifest name and version and verifies that no outside file is created.
Compile and lint, dependency audit, Linux Node.js 22/24/26, CodeQL, and zizmor checks passed on the merged public PR.
The Windows Node.js 22 full-suite job timed out in the unrelated pnpm/test/dlx.ts cache test after 512 other tests passed. The PR was merged by the maintainer; the failure did not involve the staging code.
The earlier private candidate's focused exploit regression, positive control, package compile, ESLint, and git diff --check also passed.

Compatibility

Staging and release commands are TypeScript-only. Pacquet does not expose this command family, so no Rust-side port is required.

Remaining risk

The final fs.writeFile follows a pre-existing symlink at the exact in-directory output name. That requires separate local filesystem access and is not controllable through the registry manifest traversal described here.

Written by an agent (Codex, GPT-5).

Affected versions

npm

Package	Vulnerable	Fixed in
pnpm	`>= 11.3.0, < 11.5.3`	`11.5.3`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

pnpm npm → `11.5.3`

npm

npm install pnpm@11.5.3

yarn

yarn add pnpm@11.5.3

pnpm

pnpm add pnpm@11.5.3

Severity breakdown

CVSS 3.1 7.1

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

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: Required
Scope: Unchanged
Confidentiality: None
Integrity: High
Availability: Low

Weakness

CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

How to prevent it

Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434. Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would b
Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Implementation: Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked. Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59). This includes: realpath() in C getCanonicalPath() in Java GetFullPath() in ASP.NET realpath() or abs_path() in Perl realpath() in PHP
Architecture and Design: Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid [REF-1482].
Operation: Use an application firewall that can detect attacks against this weakness. It can be beneficial in cases in which the code cannot be fixed (because it is controlled by a third party), as an emergency prevention measure while more comprehensive software assurance measures are applied, or to provide defense in depth [REF-1481].
Architecture and Design, Operation: Run your code using the lowest privileges that are required to accomplish the necessary tasks [REF-76]. If possible, create isolated accounts with limited privileges that are only used for a single task. That way, a successful attack will not immediately give the attacker access to the rest of the software or its environment. For example, database applications rarely need to run as the database administrator, especially in day-to-day operations.
Architecture and Design: When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs. For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap [REF-185] provide this capability.
Architecture and Design, Operation: Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
Architecture and Design, Operation: Store library, include, and utility files outside of the web document root, if possible. Otherwise, store them in a separate directory and use the web server's access control capabilities to prevent attackers from directly requesting them. One common practice is to define a fixed constant in each calling program, then check for the existence of the constant in the library/include file; if the constant does not exist, then the file was directly requested, and it can exit immediately. This significantly reduces the chance of an attacker being able to bypass any protection mechanisms that are in the base program but not in the include files. It will also reduce the attack surface.
Implementation: Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended). The messages should not reveal the methods that were used to determine the error. Attackers can use detailed information to refine or optimize their original attack, thereby increasing their chances of success. If errors must be captured in some detail, record them in log messages, but consider what could occur if the log messages can be viewed by attackers. Highly sensitive information such as passwords should never be saved to log files. Avoid inconsistent messaging that might accidentally tip off an attacker about internal state, such as whether a user account exists or not. In the context of path traversal, error messages which disclose path information can help attackers craft the appropriate attack strings to move through the file system hierarchy.
Operation, Implementation: When using PHP, configure the application so that it does not use register_globals. During implementation, develop the application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.

CWE-73: External Control of File Name or Path

The product allows user input to control or influence paths or file names that are used in filesystem operations.

How to prevent it

Architecture and Design: When the set of filenames is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames, and reject all other inputs. For example, ID 1 could map to "inbox.txt" and ID 2 could map to "profile.txt". Features such as the ESAPI AccessReferenceMap provide this capability.
Architecture and Design, Operation: Run your code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict all access to files within a particular directory. Examples include the Unix chroot jail and AppArmor. In general, managed code may provide some protection. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of your application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.
Architecture and Design: For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.
Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. When validating filenames, use stringent allowlists that limit the character set to be used. If feasible, only allow a single "." character in the filename to avoid weaknesses such as CWE-23, and exclude directory separators such as "/" to avoid CWE-36. Use a list of allowable file extensions, which will help to avoid CWE-434. Do not rely exclusively on a filtering mechanism that removes potentially dangerous characters. This is equivalent to a denylist, which may be incomplete (CWE-184). For example, filtering "/" is insufficient protection if the filesystem also supports the use of "\" as a directory separator. Another possible error could occur when the filtering is applied in a way that still produces dangerous data (CWE-182). For example, if "../" sequences are removed from the ".../...//" string in a sequential fashion, two instances of "../" would b
Implementation: Use a built-in path canonicalization function (such as realpath() in C) that produces the canonical version of the pathname, which effectively removes ".." sequences and symbolic links (CWE-23, CWE-59).
Installation, Operation: Use OS-level permissions and run as a low-privileged user to limit the scope of any successful attack.
Operation, Implementation: If you are using PHP, configure your application so that it does not use register_globals. During implementation, develop your application so that it does not rely on this feature, but be wary of implementing a register_globals emulation that is subject to weaknesses such as CWE-95, CWE-621, and similar issues.
Testing: Use tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session. These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.

References

Advisories

nvd.nist.gov/vuln/detail/CVE-2026-55700

Packages

github.com/pnpm/pnpm

Timeline

Jun 25, 2026 Published
Jun 29, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-vx52-2968-3vc6 pnpm: Environment secrets exfiltrated via env-placeholder expansion in proxy settings read from an untrusted pnpm-workspace.yaml	High	Also affects pnpm
GHSA-2rx9-3g3h-c2jv pnpm: pacquet trust-lockfile install can create dependency symlinks outside the project	High	Also affects pnpm
GHSA-vq4v-j7r6-jq4m pnpm: A tarball dependency's manifest `name` escapes node_modules → arbitrary file write/overwrite on install	High	Also affects pnpm
GHSA-c59q-g84q-2gj5 pnpm: Virtual store linker path traversal via unvalidated depPath name in lockfileToDepGraph	High	Also affects pnpm
GHSA-qrv3-253h-g69c pnpm: Path traversal in configDependencies env lockfile allows symlink creation outside node_modules/.pnpm-config	High	Also affects pnpm
GHSA-72r4-9c5j-mj57 pnpm: `patch-remove` could delete project-selected files outside the patches directory	High	Also affects pnpm
GHSA-fr4h-3cph-29xv pnpm: Hoisted install imports lockfile alias outside node_modules	High	Also affects pnpm
GHSA-4gxm-v5v7-fqc4 pnpm: Reserved bin name deletes PNPM_HOME during global remove	Medium	Also affects pnpm

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