How severe is GHSA-q36x-r5x4-h4q6?

GHSA-q36x-r5x4-h4q6 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-q36x-r5x4-h4q6?

GHSA-q36x-r5x4-h4q6 affects the following packages: github.com/apple/swift-nio-http2 (SwiftURL). Ecosystems affected: SwiftURL.

How do I fix GHSA-q36x-r5x4-h4q6?

Update github.com/apple/swift-nio-http2 to 1.20 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q36x-r5x4-h4q6 is resolved across your whole dependency graph.

How do I detect GHSA-q36x-r5x4-h4q6 in my SwiftURL dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/apple/swift-nio-http2. 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 GHSA-q36x-r5x4-h4q6 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 GHSA-q36x-r5x4-h4q6?

O3 pinpoints whether GHSA-q36x-r5x4-h4q6 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 GHSA-q36x-r5x4-h4q6 actively exploited in the wild?

No public exploit code has been indexed for GHSA-q36x-r5x4-h4q6 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-q36x-r5x4-h4q6?

GHSA-q36x-r5x4-h4q6 has an EPSS (Exploit Prediction Scoring System) score of 1.2%, placing it in the 66th 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-q36x-r5x4-h4q6?

GHSA-q36x-r5x4-h4q6 is classified as CWE-130 (CWE-130). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was GHSA-q36x-r5x4-h4q6 published, and has it been updated?

GHSA-q36x-r5x4-h4q6 was published on June 9, 2023 and was last updated on March 13, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

GHSA-q36x-r5x4-h4q6: Denial of service via HTTP/2 HEADERS frame…

EPSS Exploitation Probability

via FIRST.org ↗

1.2%probability of exploitation in next 30 days

Lower Risk66th percentile+0.23%

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/apple/swift-nio-http2

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

Description

A program using swift-nio-http2 is vulnerable to a denial of service attack, caused by a network peer sending a specially crafted HTTP/2 frame. This attack affects all swift-nio-http2 versions from 1.0.0 to 1.19.2. It is fixed in 1.20.0 and later releases.

This vulnerability is caused by a logical error when parsing a HTTP/2 HEADERS or HTTP/2 PUSH_PROMISE frame where the frame contains padding information without any other data. This logical error caused confusion about the size of the frame, leading to a parsing error. This parsing error immediately crashes the entire process.

Sending a HEADERS frame or PUSH_PROMISE frame with HTTP/2 padding information does not require any special permission, so any HTTP/2 connection peer may send such a frame. For clients, this means any server to which they connect may launch this attack. For servers, anyone they allow to connect to them may launch such an attack.

The attack is low-effort: it takes very little resources to send an appropriately crafted frame. The impact on availability is high: receiving the frame immediately crashes the server, dropping all in-flight connections and causing the service to need to restart. It is straightforward for an attacker to repeatedly send appropriately crafted frames, so attackers require very few resources to achieve a substantial denial of service.

The attack does not have any confidentiality or integrity risks in and of itself: swift-nio-http2 is parsing the frame in memory-safe code, so the crash is safe. However, sudden process crashes can lead to violations of invariants in services, so it is possible that this attack can be used to trigger an error condition that has confidentiality or integrity risks.

The risk can be mitigated if untrusted peers can be prevented from communicating with the service. This mitigation is not available to many services.

The issue is fixed by rewriting the parsing code to correctly handle the condition. The issue was found by automated fuzzing by oss-fuzz.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦SwiftURL	`github.com/apple/swift-nio-http2`	≥ 1.0.0&&< 1.20	1.20

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/apple/swift-nio-http2. 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/apple/swift-nio-http2 to 1.20 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q36x-r5x4-h4q6 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 GHSA-q36x-r5x4-h4q6 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 GHSA-q36x-r5x4-h4q6. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

A program using swift-nio-http2 is vulnerable to a denial of service attack, caused by a network peer sending a specially crafted HTTP/2 frame. This attack affects all swift-nio-http2 versions from 1.0.0 to 1.19.2. It is fixed in 1.20.0 and later releases. This vulnerability is caused by a logical error when parsing a HTTP/2 HEADERS or HTTP/2 PUSH_PROMISE frame where the frame contains padding information without any other data. This logical error caused confusion about the size of the frame, leading to a parsing error. This parsing error immediately crashes the entire process. Sending a HEA

O3 Security · Impact-Aware SCA

Is GHSA-q36x-r5x4-h4q6 in your dependencies?

O3 detects GHSA-q36x-r5x4-h4q6 across SwiftURL 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

GHSA-q36x-r5x4-h4q6