Sliver: Unauthenticated Memory Exhaustion Denial of Service in Sliver HTTP(S) Listener PNG Decoder

{
  "id": "dd622bfed01ac13ee2bc289aa4ac6c8acd4cc0cdf7ee8576b98804c68746f8be",
  "url": "https://osv.dev/vulnerability/GHSA-663m-7x7m-g4fw",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Sliver: Unauthenticated Memory Exhaustion Denial of Service in Sliver HTTP(S) Listener PNG Decoder",
    "summary": "### Summary Sliver is vulnerable to a Denial of Service (DOS) attack because there is no cap in the size of a PNG file that can be sent to an open http listener and there is a small amount of possible nonces. This vulnerability lets the attacker completely max out the RAM of the machine running server, leading to a complete loss of availability. ### Details The first vulnerability is that the amount of possible nonces is 65,537. This is found in `server/encoders/encoders.go` ```go const ( EncoderModulus = uint64(65537) ) ``` The second vulnerability is there is no limit to how many pixels the PNG encoder will accept from an unauthenticated user. This is found in: `util/encoders/images.go` ```go func (p PNGEncoder) Encode(data []byte) ([]byte, error) { img := imageFromBytes(data) var buf bytes.Buffer encoder.Encode(&buf, img) return buf.Bytes(), nil } func (p PNGEncoder) Decode(data []byte) ([]byte, error) { buf := bytes.NewBuffer(data) img, err := png.Decode(buf) if err != nil { return nil, err } return bytesFromImage(img), nil } ``` ### PoC The first step to reproduce this vulnerability is building a docker container to make sure no harm is caused. Get the latest version of Sliver (Currently 1.7.3) ```bash git clone https://github.com/BishopFox/sliver.git ``` Build the Docker container: ```bash cd sliver docker build -t sliver-test:local -f Dockerfile . ``` Run the Docker container with a memory cap for example 4GB: ```bash docker run --rm \\ --name sliver-test \\ --memory=4g ",
    "evidence": "osv:GHSA-663m-7x7m-g4fw",
    "products": [
      {
        "name": {
          "value": "github.com/BishopFox/sliver",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "1.7.6",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "GHSA-663m-7x7m-g4fw",
      "aliases": [
        "CVE-2026-77622",
        "GHSA-663m-7x7m-g4fw",
        "GO-2026-6777"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "SEMVER",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "1.7.6"
                }
              ]
            }
          ],
          "package": {
            "name": "github.com/BishopFox/sliver",
            "purl": "pkg:golang/github.com/BishopFox/sliver",
            "ecosystem": "Go"
          },
          "database_specific": {
            "source": "https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/10/GHSA-663m-7x7m-g4fw/GHSA-663m-7x7m-g4fw.json"
          }
        }
      ],
      "modified": "2026-10-19T21:40:45.149589702Z",
      "provider": "osv",
      "references": [
        "https://github.com/BishopFox/sliver/security/advisories/GHSA-663m-7x7m-g4fw",
        "https://github.com/BishopFox/sliver/commit/80273462bd8b2a3cd724d2d6d0301a0cabfa977d",
        "https://github.com/BishopFox/sliver",
        "https://github.com/BishopFox/sliver/releases/tag/v1.7.6"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-770"
        ],
        "severity": "HIGH",
        "github_reviewed": true,
        "nvd_published_at": null,
        "github_reviewed_at": "2026-10-15T20:09:33Z"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-77622",
        "evidence": "/aliases"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/database_specific/severity"
  },
  "source_id": "core-osv",
  "document_id": 376734,
  "published_at": "2026-10-15T20:09:33+00:00"
}