How severe is GHSA-wgrg-5h56-jg27?

No CVSS score has been assigned to GHSA-wgrg-5h56-jg27 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-wgrg-5h56-jg27?

GHSA-wgrg-5h56-jg27 affects the following packages: nix (crates.io), nix (crates.io), nix (crates.io). Ecosystems affected: crates.io.

How do I fix GHSA-wgrg-5h56-jg27?

Update nix to 0.20.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wgrg-5h56-jg27 is resolved across your whole dependency graph.

How do I detect GHSA-wgrg-5h56-jg27 in my crates.io dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nix, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-wgrg-5h56-jg27 if there is no patch (or I can't update yet)?

Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

Is GHSA-wgrg-5h56-jg27 actively exploited in the wild?

No public exploit code has been indexed for GHSA-wgrg-5h56-jg27 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-wgrg-5h56-jg27?

GHSA-wgrg-5h56-jg27 has an EPSS (Exploit Prediction Scoring System) score of 1.7%, placing it in the 77th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-wgrg-5h56-jg27?

GHSA-wgrg-5h56-jg27 is classified as Out-of-bounds Write (CWE-787). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-wgrg-5h56-jg27 published, and has it been updated?

GHSA-wgrg-5h56-jg27 was published on June 17, 2022 and was last updated on September 10, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🦀 crates.io

Not in CISA KEV

Out-of-bounds write in nix::unistd::getgrouplistGHSA-wgrg-5h56-jg27

GHSA-wgrg-5h56-jg27 is a Out-of-bounds Write vulnerability in nix. A fix is available for nix — see the affected versions and patch details below.

Also known asCVE-2021-45707 GHSA-76w9-p8mg-j927RUSTSEC-2021-0119

Published

Jun 17, 2022

Updated

Sep 10, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Exploitation data as of Oct 27, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.7%probability of exploitation in next 30 days

Lower Risk+0.04%

Lower risk than most CVEs77th percentile — riskier than 77% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

3 pkgs affected

🦀nix🦀nix🦀nix

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.

Description

On certain platforms, if a user has more than 16 groups, the nix::unistd::getgrouplist function will call the libc getgrouplist function with a length parameter greater than the size of the buffer it provides, resulting in an out-of-bounds write and memory corruption.

The libc getgrouplist function takes an in/out parameter ngroups specifying the size of the group buffer. When the buffer is too small to hold all of the reqested user's group memberships, some libc implementations, including glibc and Solaris libc, will modify ngroups to indicate the actual number of groups for the user, in addition to returning an error. The version of nix::unistd::getgrouplist in nix 0.16.0 and up will resize the buffer to twice its size, but will not read or modify the ngroups variable. Thus, if the user has more than twice as many groups as the initial buffer size of 8, the next call to getgrouplist will then write past the end of the buffer.

The issue would require editing /etc/groups to exploit, which is usually only editable by the root user.

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
🦀crates.io	`nix`	≥ 0.16.0&&< 0.20.2	0.20.2`cargo update -p nix --precise 0.20.2`
🦀crates.io	`nix`	≥ 0.21.0&&< 0.21.2	0.21.2`cargo update -p nix --precise 0.21.2`
🦀crates.io	`nix`	≥ 0.22.0&&< 0.22.2	0.22.2`cargo update -p nix --precise 0.22.2`

Affected Products

1 product · 3 configurations

Application

nixnix_project

≥ 0.22.0 && < 0.22.2

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nix, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update nix to 0.20.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-wgrg-5h56-jg27 is resolved across your whole dependency graph.
Workarounds
Constrain what reaches the vulnerable code: limit the size and shape of untrusted input, isolate the affected component in a sandboxed or least-privileged process, and enable the platform's memory-safety mitigations (ASLR, stack protector, hardened allocator) so an out-of-bounds access is more likely to fail closed than to be exploitable.

Frequently Asked Questions

On certain platforms, if a user has more than 16 groups, the `nix::unistd::getgrouplist` function will call the libc `getgrouplist` function with a length parameter greater than the size of the buffer it provides, resulting in an out-of-bounds write and memory corruption. The libc `getgrouplist` function takes an in/out parameter `ngroups` specifying the size of the group buffer. When the buffer is too small to hold all of the reqested user's group memberships, some libc implementations, including glibc and Solaris libc, will modify `ngroups` to indicate the actual number of groups for the us

O3 Security · Impact-Aware SCA

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