GHSA-93mq-9ffx-83m2 is a high-severity (CVSS 7.5) CWE-770 vulnerability in github.com/expr-lang/expr. A fix is available for github.com/expr-lang/expr — see the affected versions and patch details below.
Memory Exhaustion in Expr Parser with Unrestricted Input
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-93mq-9ffx-83m2.
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.
How urgent is this, really
GHSA-93mq-9ffx-83m2 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,238 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/expr-lang/exprReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Impact
If the Expr expression parser is given an unbounded input string, it will attempt to compile the entire string and generate an Abstract Syntax Tree (AST) node for each part of the expression. In scenarios where input size isn’t limited, a malicious or inadvertent extremely large expression can consume excessive memory as the parser builds a huge AST. This can ultimately lead to excessive memory usage and an Out-Of-Memory (OOM) crash of the process. This issue is relatively uncommon and will only manifest when there are no restrictions on the input size, i.e. the expression length is allowed to grow arbitrarily large. In typical use cases where inputs are bounded or validated, this problem would not occur.
Patches
The problem has been patched in the latest versions of the Expr library. The fix introduces compile-time limits on the number of AST nodes and memory usage during parsing, preventing any single expression from exhausting resources. Users should upgrade to Expr version 1.17.0 or later, as this release includes the new node budget and memory limit safeguards. Upgrading to v1.17.0 ensures that extremely deep or large expressions are detected and safely aborted during compilation, avoiding the OOM condition.
Workarounds
For users who cannot immediately upgrade, the recommended workaround is to impose an input size restriction before parsing. In practice, this means validating or limiting the length of expression strings that your application will accept. For example, set a maximum allowable number of characters (or nodes) for any expression and reject or truncate inputs that exceed this limit. By ensuring no unbounded-length expression is ever fed into the parser, you can prevent the parser from constructing a pathologically large AST and avoid potential memory exhaustion. In short, pre-validate and cap input size as a safeguard in the absence of the patch.
References
- #762
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/expr-lang/expr | all versions | 1.17.0go get github.com/expr-lang/expr@v1.17.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/expr-lang/expr, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/expr-lang/expr to 1.17.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-93mq-9ffx-83m2 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-93mq-9ffx-83m2 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-93mq-9ffx-83m2. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 10 | opentelemetry-collector-0:0.107.0-9.el10_0 | RHSA-2025:7479 |
| Red Hat Enterprise Linux 9 | opentelemetry-collector-0:0.107.0-8.el9_5 | RHSA-2025:3335 |
| Red Hat Enterprise Linux 9 | opentelemetry-collector-0:0.107.0-8.el9_6 | RHSA-2025:7407 |
| Red Hat Enterprise Linux 9.4 Extended Update Support | opentelemetry-collector-0:0.107.0-7.el9_4 | RHSA-2025:3593 |
| Red Hat OpenShift GitOps 1.15 | openshift-gitops-1/argocd-extensions-rhel8:v1.15.2-4 | RHSA-2025:7753 |
| Custom Metric Autoscaler operator for Red Hat Openshift 2.15 | custom-metrics-autoscaler/custom-metrics-autoscaler-adapter-rhel9:2.15.1-1744845058 | RHSA-2025:3993 |
| Red Hat OpenShift distributed tracing 3.5.1 | rhosdt/tempo-rhel8:rhosdt-3.5-1744102053 | RHSA-2025:3740 |
| Red Hat OpenShift distributed tracing 3.5.1 | rhosdt/opentelemetry-collector-rhel8:rhosdt-3.5-1744103234 | RHSA-2025:3743 |
Frequently Asked Questions
Is GHSA-93mq-9ffx-83m2 in your dependencies?
O3 Security finds GHSA-93mq-9ffx-83m2 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.