CVE-2026-55487 is a high-severity security vulnerability in pnpm (npm), affecting versions < 10.34.2. It is fixed in 10.34.2, 11.5.3.
Summary Keep build approval for opaque dependency sources byte-exact for GHSA-5wx6-mg75-v57r / CAND-PNPM-123. Merged upstream commit bf1b731ee6 fixed the original name-only approval bypass by making build policy consume the resolved dependency identity. One collision remained: the generic peer-suffix normalizer also stripped parenthesized text from git, URL, tarball, file, and other opaque locators. Approval for one source string could therefore authorize a different attacker-controlled source whose locator normalized to the same value. Security boundary Registry dependency identities still normalize legitimate peer suffixes and retain patch hashes. Git, URL, tarball, file, directory, and otherwise opaque identities must match the complete resolved locator byte for byte. Explicit denials use the same normalization as approvals. Ignored-build output preserves the exact opaque identity, so the key pnpm asks a user to approve is the key policy later checks. TypeScript pnpm and pacquet implement the same distinction between registry and opaque identities. Exploit replay With allowBuilds approving foo@https://host/pkg.tgz, the upstream implementation also accepted foo@https://host/pkg.tgz(evil) because both passed through peer-suffix removal. An independent review found a second Rust-only form: foo@https://host/[email protected](good) and foo@https://host/[email protected](evil) collided because the parser selected the final @ and misclassified the opaque URL as a registry package. A final review found the same parser hazard in source-only locators ending in a semver-looking tail: approval for https://host/[email protected] could collapse https://host/[email protected](evil). The final patch rejects all three collision forms, applies the same exactness to deny rules, accepts exact opaque keys as positive controls, and continues to accept registry packages approved without their peer suffixes. Files changed building/policy/src/index.ts and building/policy/test/index.ts normalize only parsed registry identities and retain exact opaque keys. pacquet/crates/package-manager/src/buildmodules.rs passes snapshot identities to policy, matches TypeScript package-separator parsing, and preserves opaque locators. pacquet/crates/package-manager/src/buildmodules/tests.rs covers exact approval and denial, all three collision forms, ignored-build output, and registry peer compatibility. .changeset/quiet-opaque-build-identities.md records patch releases for @pnpm/building.policy and pnpm. Commands run Validation The TypeScript policy suite passed all 16 tests. The final pacquet build-policy suite passed all 49 tests. The new Rust regression reproduced the extra-@ collision before the additive fix and passed afterward. Exact opaque approval and denial, source-only semver-tail collision rejection, registry peer normalization, and ignored-build reporting all have paired tests. ESLint passed on the changed TypeScript source and test files. Rust formatting and diff checks passed; the branch is clean and consists of three focused security commits plus additive merges of upstream through 84bb4b1a046f3a659de1c9aab1d45dcf814124ce. The focused TypeScript suite and ESLint ran directly through the installed harness. The isolated project build cannot resolve workspace packages without a local install, and the configured registry gateway returns HTTP 403 while fetching @pnpm/[email protected]; no candidate-focused test failed. Patches 10.34.2: https://github.com/pnpm/pnpm/commit/14bceb1e0b2a71f4f670774db261feb03f38ec23 11.5.3: https://github.com/pnpm/pnpm/commit/bf1b731ee6c0ea98709e671ff0f46bf654480ab8 Compatibility Registry package approvals keep their existing form. Opaque dependencies that were approved through a normalized parenthesized variant must now use the exact key shown in pnpm's ignored-build output. This is the intended trust-boundary change; no package-resolution or artifact format changes. CI note GitHub intentionally does not run status checks on temporary private-fork pull requests. The complete policy suites, formatting, and diff checks above are the applicable validation: https://docs.github.com/code-security/security-advisories/collaborating-in-a-temporary-private-fork-to-resolve-a-security-vulnerability Written by an agent (Codex, GPT-5).
CVE-2026-55487 has a CVSS score of 7.5 (High). The vector is network-reachable, no privileges required, and user interaction required. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment.
A fixed version is available (10.34.2, 11.5.3). Upgrading removes the vulnerable code path.
npm
pnpm (< 10.34.2)pnpm (>= 11.0.0, < 11.5.3)pnpm → 10.34.2 (npm)pnpm → 11.5.3 (npm)Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter instead of chasing every advisory.
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pnpm to 10.34.2 or laterpnpm to 11.5.3 or laterKodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
CVE-2026-55487 is a high-severity security vulnerability in pnpm (npm), affecting versions < 10.34.2. It is fixed in 10.34.2, 11.5.3.
CVE-2026-55487 has a CVSS score of 7.5 (High). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
pnpm (npm) versions < 10.34.2 is affected.
Yes. CVE-2026-55487 is fixed in 10.34.2, 11.5.3. Upgrade to this version or later.
Whether CVE-2026-55487 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
pnpm to 10.34.2 or laterpnpm to 11.5.3 or later