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yersinia

2005/10/26 open-source

Yersinia is a framework for layer 2 attacks targeting protocols including STPSTPSpanning Tree Protocol, an IEEE standard (802.1D) that prevents Layer 2 network loops by electing a root bridge and blocking redundant switch paths, keeping Ethernet networks stable under failure conditions., CDPCDPCisco Discovery Protocol, a Cisco-proprietary Layer 2 protocol that advertises device identity, capabilities, and topology between directly connected Cisco gear, giving cyber tools a passive way to map network infrastructure., DHCP, DTP, VTP, HSRP, and 802.1Q802.1QAn IEEE standard that adds a 4-byte VLAN tag to Ethernet frames, letting a single physical link carry traffic for multiple isolated networks. Cyber tools use it to capture or inject traffic on specific VLANs..

source ↗ rss ↗ What is a cyber toolchain? last repo push Sep 15, 2023

Summary

yersinia is an open-source command-line tool for attacking layer 2 network protocols, sending crafted packets to abuse weaknesses in STP, CDP, DHCP, VLAN trunking and similar protocols. It runs interactively from a terminal or via scripted command-line invocation, letting you launch specific attacks like spanning-tree root claims or DHCP rogue-server floods against switches and routers. It is aimed at penetration testers and network engineers who need to test how switching infrastructure holds up against layer 2 abuse rather than at general vulnerability scanning teams. It sits in the network protocol exploitation category, alongside other packet-crafting attack tools rather than reconnaissance or scanning software. Development dates back to 2013 with 15 contributors, but there have been no commits in the past year, so anyone adopting it should expect a stable but effectively dormant codebase.

Yersinia is a framework for layer 2 attacks targeting protocols including STP, CDP, DHCP, DTP, VTP, HSRP, and 802.1Q.

How yersinia helps

Will the switches near me actually recalculate their spanning-tree topology if a rogue root appears?

floods the segment with configuration BPDUs claiming root path cost zero and a randomly generated bridge ID, forcing neighboring switches to keep re-hearing a new root and recalculate their STP engine, visible in their logs as repeated root-change messages

Can I force a topology change without waiting for a real link event?

sends topology change notification BPDUs continuously so the root switch acknowledges the change and propagates it to every member of the tree, each one forced to recompute

Does the DHCP server on this segment get confused by a rogue server on the wire?

launches a rogue DHCP server attack that answers client requests directly, showing whether the real server's leases get contested

Is this switch port trusting CDP announcements it shouldn't?

crafts and sends CDP packets so you can watch whether the neighboring device accepts and displays fabricated neighbor information

Can a host on this VLAN reach traffic it should be segmented from?

drives 802.1Q trunking or hopping frames onto the wire so you can check whether the switch forwards them across VLAN boundaries it should be enforcing

Languages

Not documented

Score card

  1. Shipping velocity releases a month, last 12 months
  2. Documentation quality release-notes rubric, 0–100
  3. Breaking-change discipline how rarely a release breaks users, and notice given
  4. Maintenance risk quiet time against its own cadence, maintainers
  5. Innovation & surface new capabilities, API and MCP surface
  6. Community health
  7. Contributor trend distinct committers, this year against last
  8. Maintainer concentration bus factor now against a year ago
  9. Issue backlog trend issues closed per issue opened, 12 months
  10. Responsiveness median time to a maintainer’s first reply

Nine scores for yersinia, each built from the releases, notes and API history this site tracks — and, on Researcher and Business, where it stands among every measured tool in its category and how that has moved.

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Each score is 0–100 on a published rubric, derived from data this site already shows. A dimension we cannot measure says so — it is never scored 0 and never enters a rank.

How this is scored
  • Shipping velocity — releases a month over the last 12 months, on a log scale where 16 a month scores 100. Needs 3 releases in the window.
  • Documentation quality — the release-notes rubric published on the analytics page, unchanged.
  • Breaking-change discipline — the share of releases carrying a breaking change (none scores 100, half or more scores 0). Only projects that label breaking changes are measured: a clean record cannot be told from an unlabelled one.
  • Maintenance risk — quiet time measured against the tool's own release cadence (quiet longer than 90 days and three typical gaps scores 0), plus the number of active maintainers and whether contributors are growing, where known. Higher is lower risk.
  • Innovation & surface — new capabilities in the feature ledger this year, API and MCP operations added, and the share of commits that are features: the mean of whichever we hold.
  • Community health (open-source tools only) — each is a direction, not a size: contributors this year against last, the bus factor now against a year ago, and issues closed per issue opened, where steady scores 50, doubled 100 and halved 0; plus the median time to a maintainer's first reply (an hour scores about 100, a month or more 0). A commercial card has no repository and carries none of the four.
  • Documented delivery (commercial tools) — when a vendor's documented new capabilities have slowed against its own baseline, that counts against the overall standing as heavily as two low dimensions. Steady delivery, or too little history to judge, leaves the standing alone; it is never a sixth score.
  • Open-source tools are scored on repository signals; commercial tools on their published changelog. Ranks compare tools within one category and one profile and need at least five measured peers; the overall standing needs three ranked dimensions. Best-in-breed or consolidator is a shape, not a quality, and is never scored.

Release-note detail over time

See how much detail yersinia puts in its release notes, quarter by quarter, and compare it with tracked tools in the same category. This history uses up to ten retained, reviewed notes per tool; sparse or blank older quarters may reflect that limit.

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Releases

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4 entries

  1. October 20262
  3. October 20051
  5. September 20051
    Show

    4 entries

    1. docs update Oct 10, 2026 · issue 101

      Yersinia gains cross-compilation support with custom libpcap and libnet paths for arm64 and mips64 targets.⁠︀︄︇︀︅︉︀︅︀︀︃︀︀︅︅︀︅︊︀︄︆︀︃︄⁠

      • Supports cross-compiling yersinia out-of-the-box by specifying custom libpcap and libnet paths, enabling native arm64 and mips64 cross-compiled binary builds.⁠︀︄︇︀︅︉︀︅︀︀︃︀︀︅︅︀︅︊︀︄︆︀︃︄⁠

      1 detail in Everything

    2. docs update Oct 10, 2026 · issue 101

      Yersinia re-enables DHCP Decline message support, verified via packet capturepacket captureA packet capture, recorded network packets that can be inspected later. Analysts use it to reconstruct communication and investigate protocol behavior or suspicious traffic..⁠︀︄︇︀︅︉︀︅︀︀︃︀︀︅︅︀︅︊︀︄︆︀︃︄⁠

      • Supports sending DHCP Decline messages, re-enabling previously disabled functionality verified with packet capture.⁠︀︄︇︀︅︉︀︅︀︀︃︀︀︅︅︀︅︊︀︄︆︀︃︄⁠

      1 detail in Everything

    3. 2005/10/26 Oct 26, 2005 · release notes

      Yersinia v2005/10/26 introduces redesigned CLI set commands for DTP, VTP, 802.1Q802.1QAn IEEE standard that adds a 4-byte VLAN tag to Ethernet frames, letting a single physical link carry traffic for multiple isolated networks. Cyber tools use it to capture or inject traffic on specific VLANs., HSRP and CDPCDPCisco Discovery Protocol, a Cisco-proprietary Layer 2 protocol that advertises device identity, capabilities, and topology between directly connected Cisco gear, giving cyber tools a passive way to map network infrastructure..

      └──▷ GET THIS VERSION 
      $ git clone --branch 2005/10/26 https://github.com/tomac/yersinia.git
# already have the repo? check out this version:
$ git checkout 2005/10/26
      • Adds new design for DTP CLI command set
      • Adds new design for VTP CLI command set
      • Adds new design for 802.1Q CLI command set
      • Adds new design for HSRP CLI command set
      • Adds new design for CDP CLI command set

      5 details in Everything

    4. 2005/09/23 Sep 23, 2005 · release notes

      Additions to configuration via daemon port setting

      └──▷ GET THIS VERSION 
      $ git clone --branch 2005/09/23 https://github.com/tomac/yersinia.git
# already have the repo? check out this version:
$ git checkout 2005/09/23

    Project health

    Issue, contributor and maintainer activity in tomac/yersinia, 2023-10 – 2026-09, as of 2026-09-25. Twelve-month figures first; the trend lines run the whole window.

    1. Contributors 0 ±0 vs prior 12 months
    2. Maintainers 0 +0 joined · −0 left, last 12 months
    3. Bus factor 0 committers behind half the commits
    4. Community-filed 100% of issues opened, last 12 months
    5. Median time to close not measured issues closed, last 12 months
    6. Open backlog 21 of 60 issues ever filed
    1. Issues opened / month 0 · 0 communitymaintainers
    2. Open backlog 21
    3. Contributors / month 0
    4. Commits / month 0
    5. Stars 870
    Issue themes, last 12 months
    • other 100%

    Counts from the project's public repository and git history; no individuals are identified. Maintainers are the committers covering 80% of the last year's commits. how we measure this

    Libraries its release ships

    What its latest release locks, checked against known advisories.

    None of its release's images build from a lockfile we can read.

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