GHSA-hjr9-wj7v-7hv8: Github.com/bishopfox/sliver Sliver Vulnerable To Pre-Auth Memory Vulnerability

MODERATE
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CWE-770
Published
Advisory Summary

GHSA-hjr9-wj7v-7hv8 is a MODERATE sliver vulnerable to pre-auth memory vulnerability (CWE-770: Allocation of Resources Without Limits or Throttling) affecting Github.com/bishopfox/sliver libraries in the Go ecosystem. The issue involves sliver vulnerable to pre-auth memory exhaustion via noencoder bypass. Remediation is available in the latest vendor maintenance releases.

GHSA-hjr9-wj7v-7hv8 at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-hjr9-wj7v-7hv8
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-770: Allocation of Resources Without Limits or Throttling
Affected Product Github.com/bishopfox/sliver
Package Ecosystem Go
Published Date
Last Updated

How to Fix GHSA-hjr9-wj7v-7hv8

To remediate this vulnerability, upgrade all affected Github.com/bishopfox/sliver dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

github.com/bishopfox/sliver fixed: Latest secure release 
Upgrade github.com/bishopfox/sliver to Latest secure release
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for github.com/bishopfox/sliver

How to Check if You Are Affected

To determine whether your application is affected by GHSA-hjr9-wj7v-7hv8, inspect your project dependencies for Github.com/bishopfox/sliver:

inspect dependencies for github.com/bishopfox/sliver

Analyze the terminal output to locate any version of Github.com/bishopfox/sliver in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than the patched release), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-770: Allocation of Resources Without Limits or Throttling, where the product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated. In Github.com/bishopfox/sliver, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Summary A specially crafted nonce routes unauthenticated requests through the NoEncoder path, where `startSessionHandler()` reads the entire request body without limits, allowing attacker-driven memory exhaustion and process crash. ### Details - `server/encoders/encoders.go`: `EncoderFromNonce()` returns NoEncoder when `nonce % 65537 == 0` (lines 254-264); NoEncoder is a passthrough (`util/encoders/nop.go:22-32`). - `server/c2/http.go`: `anonymousHandler()` routes requests with any encoder (including NoEncoder) to `startSessionHandler()` (lines 551-562). - `server/c2/http.go`: `startSessionHandler()` uses `io.ReadAll(req.Body)` without a size cap (lines 564-643), unlike the authenticated path that uses `io.LimitedReader` (`readReqBody()`, lines 708-732). ### PoC An attacker could send an HTTP POST with a nonce that is a multiple of 65537 (e.g., ?q=65537) so it is handled by startSessionHandler() with a NoEncoder, and advertise a very large Content-Length while streaming data. Because this handler uses io.ReadAll(req.Body) without a size limit, the server is expected to allocate large amounts of memory and may exhaust available RAM, leading to process termination on typical deployments. ### Impact Unauthenticated remote DoS: attacker can crash the Sliver HTTP listener, dropping all active sessions and locking out operators until restart. No credentials or non-default config required.

GHSA-hjr9-wj7v-7hv8 Affected Github.com/bishopfox/sliver Versions

1 component(s)
Product / Package Ecosystem Affected Versions Fixed Version
github.com/bishopfox/sliver
golang/github.com/bishopfox/sliver
Go
≥ 1.5.0
≤ 1.5.44

References

GitHub Advisory / Wiki ADVISORY
https://github.com/BishopFox/sliver/security/advisories/GHSA-hjr9-wj7v-7hv8
Github.com/bishopfox/sliver Source Repository REPOSITORY
https://github.com/BishopFox/sliver

Frequently Asked Questions

What is GHSA-hjr9-wj7v-7hv8?
GHSA-hjr9-wj7v-7hv8 is a security vulnerability in Github.com/bishopfox/sliver involving Sliver Vulnerable to Pre-Auth Memory Exhaustion via NoEncoder Bypass under CWE-770: Allocation of Resources Without Limits or Throttling.
Which Github.com/bishopfox/sliver versions are affected?
Affected versions include releases prior to current release patches across affected packages: github.com/bishopfox/sliver.
What version fixes GHSA-hjr9-wj7v-7hv8?
Upgrading to current release patches (or the latest patched release for your respective branch) resolves the vulnerability.
Is github.com/bishopfox/sliver affected?
Yes, github.com/bishopfox/sliver is affected in releases prior to Latest secure release. Upgrade your dependency to Latest secure release or later.
What CWE is associated with GHSA-hjr9-wj7v-7hv8?
GHSA-hjr9-wj7v-7hv8 is classified under CWE-770: Allocation of Resources Without Limits or Throttling (The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.).
How can I check Go dependencies for GHSA-hjr9-wj7v-7hv8?
Run the dependency tree command: 'inspect dependencies for github.com/bishopfox/sliver'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-hjr9-wj7v-7hv8",
  "modified" : "2026-01-05T19:43:06Z",
  "published" : "2026-01-05T19:43:06Z",
  "aliases" : [ ],
  "summary" : "Sliver Vulnerable to Pre-Auth Memory Exhaustion via NoEncoder Bypass",
  "details" : "### Summary\nA specially crafted nonce routes unauthenticated requests through the NoEncoder path, where `startSessionHandler()` reads the entire request body without limits, allowing attacker-driven memory exhaustion and process crash.\n\n### Details\n- `server/encoders/encoders.go`: `EncoderFromNonce()` returns NoEncoder when `nonce % 65537 == 0` (lines 254-264); NoEncoder is a passthrough (`util/encoders/nop.go:22-32`).\n- `server/c2/http.go`: `anonymousHandler()` routes requests with any encoder (including NoEncoder) to `startSessionHandler()` (lines 551-562).\n- `server/c2/http.go`: `startSessionHandler()` uses `io.ReadAll(req.Body)` without a size cap (lines 564-643), unlike the authenticated path that uses `io.LimitedReader` (`readReqBody()`, lines 708-732).\n\n### PoC\nAn attacker could send an HTTP POST with a nonce that is a multiple of 65537 (e.g., ?q=65537) so it is handled by startSessionHandler() with a NoEncoder, and advertise a very large Content-Length while streaming data. Because this handler uses io.ReadAll(req.Body) without a size limit, the server is expected to allocate large amounts of memory and may exhaust available RAM, leading to process termination on typical deployments.\n\n### Impact\nUnauthenticated remote DoS: attacker can crash the Sliver HTTP listener, dropping all active sessions and locking out operators until restart. No credentials or non-default config required.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:P"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/bishopfox/sliver"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "1.5.0"
      }, {
        "last_affected" : "1.5.44"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/BishopFox/sliver/security/advisories/GHSA-hjr9-wj7v-7hv8"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/BishopFox/sliver"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-01-05T19:43:06Z",
    "nvd_published_at" : null
  }
}