GHSA-wgrg-5h56-jg27 — nix
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.
Out-of-bounds write in nix::unistd::getgrouplist
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
nix🦀nix🦀nixReal-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
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | nix | ≥ 0.16.0&&< 0.20.2 | 0.20.2cargo update -p nix --precise 0.20.2 |
| 🦀crates.io | nix | ≥ 0.21.0&&< 0.21.2 | 0.21.2cargo update -p nix --precise 0.21.2 |
| 🦀crates.io | nix | ≥ 0.22.0&&< 0.22.2 | 0.22.2cargo update -p nix --precise 0.22.2 |
Detection & mitigation playbook
Open-source dependencyDetect
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
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-wgrg-5h56-jg27 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-wgrg-5h56-jg27. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-wgrg-5h56-jg27 in your dependencies?
O3 Security finds GHSA-wgrg-5h56-jg27 across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.