How severe is CVE-2026-31959?

CVE-2026-31959 has a CVSS score of 5.3/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2026-31959?

CVE-2026-31959 affects the following packages: github.com/anchore/quill (Go). Ecosystems affected: Go.

How do I fix CVE-2026-31959?

Update github.com/anchore/quill to 0.7.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-31959 is resolved across your whole dependency graph.

How do I detect CVE-2026-31959 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/anchore/quill. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate CVE-2026-31959 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2026-31959?

O3 pinpoints whether CVE-2026-31959 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-31959 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-31959 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 CVE-2026-31959?

CVE-2026-31959 has an EPSS (Exploit Prediction Scoring System) score of 0.1%, placing it in the 1th 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 CVE-2026-31959?

CVE-2026-31959 is classified as Server-Side Request Forgery (SSRF) (CWE-918). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-31959 published, and has it been updated?

CVE-2026-31959 was published on March 11, 2026 and was last updated on April 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.

CVE-2026-31959: quill Server-Side Request Forgery (Medium 5.3)

EPSS Exploitation Probability

via FIRST.org ↗

0.1%probability of exploitation in next 30 days

Lower Risk1th percentile+0.08%

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.

Blast Radius

1 pkg affected

🐹github.com/anchore/quill

Real-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

Quill provides simple mac binary signing and notarization from any platform. Quill before version v0.7.1 contains a Server-Side Request Forgery (SSRF) vulnerability when attempting to fetch the Apple notarization submission logs. Exploitation requires the ability to modify API responses from Apple's notarization service, which is not possible under standard network conditions due to HTTPS with proper TLS certificate validation; however, environments with TLS-intercepting proxies (common in corporate networks), compromised certificate authorities, or other trust boundary violations are at risk. When retrieving submission logs, Quill fetches a URL provided in the API response without validating that the scheme is https or that the host does not point to a local or multicast IP address. An attacker who can tamper with the response can supply an arbitrary URL, causing the Quill client to issue HTTP or HTTPS requests to attacker-controlled or internal network destinations. This could lead to exfiltration of sensitive data such as cloud provider credentials or internal service responses. Both the Quill CLI and library are affected when used to retrieve notarization submission logs. This vulnerability is fixed in 0.7.1.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/anchore/quill`	all versions	0.7.1

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/anchore/quill. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update github.com/anchore/quill to 0.7.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-31959 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 pinpoints whether CVE-2026-31959 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to CVE-2026-31959. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Quill provides simple mac binary signing and notarization from any platform. Quill before version v0.7.1 contains a Server-Side Request Forgery (SSRF) vulnerability when attempting to fetch the Apple notarization submission logs. Exploitation requires the ability to modify API responses from Apple's notarization service, which is not possible under standard network conditions due to HTTPS with proper TLS certificate validation; however, environments with TLS-intercepting proxies (common in corporate networks), compromised certificate authorities, or other trust boundary violations are at risk.

O3 Security · Impact-Aware SCA

Is CVE-2026-31959 in your dependencies?

O3 detects CVE-2026-31959 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

Scan my dependencies How O3 SCA works

CVE-2026-31959