Former Ethereum ($ETH) Foundation Employee Sues Vitalik Buterin Over Firing After Cancer Diagnosis

Published November 10, 2026, 4:42 PM PKT. Based on the complaint filed in US District Court for the District of Colorado, and reporting from Unchained and Cointelegraph, both published November 9 and 10, 2026. The claims below are allegations in a lawsuit. They have not been tested in court, and the defendants had not responded publicly as of November 9.

A former Ethereum ($ETH) Foundation employee sued the foundation, co-founder Vitalik Buterin and four others on November 4, 2026, alleging she was fired thirteen days after telling leadership in writing that she had ovarian cancer, and twelve days after co-organizing a staff letter that challenged the foundation's new Mandate. Kayleen Fulton, who led the foundation's Protocol Support team and is known in the Ethereum ($ETH) community as "Nixo", filed the complaint in the United States District Court for the District of Colorado, case number 1:26-cv-05818.

The complaint names six defendants: Stiftung Ethereum, the Swiss foundation that operates as the Ethereum ($ETH) Foundation; Ethereum Asia Pacific Limited, the Singapore affiliate on whose behalf Fulton was hired; Lightsource HR Global and Vensure Employer Services, two firms that handled her hiring, payroll and benefits; Bastian Aue, then a co-executive director; and Buterin, a Stiftung Ethereum board member sued in his individual capacity. Buterin is a defendant in five of the eleven claims, by Unchained's count.

Fulton seeks back and front pay plus compensatory and punitive damages, with no dollar figure attached, according to Unchained. The foundation laid off 54 employees in June, days after Hsiao-Wei Wang stepped down as co-executive director, Unchained reported.

Thirteen days from disclosure to dismissal

The complaint lays out a tight timeline. Fulton was diagnosed with ovarian cancer on March 19, 2026, the day before the foundation issued its ultimatum over the Mandate. On March 24 she disclosed the diagnosis in an email to Aue, two board members and the foundation's People Operations staff, the complaint says, writing that she was beginning "an active treatment plan" and asking that her employment status not be altered. She asked them to confirm receipt.

Aue and both board members never responded, the complaint says. The head of People Operations sent a two-line personal note, and no one asked about leave, accommodation or her treatment, according to the complaint. No one provided the notices the Family and Medical Leave Act requires, it says.

The next day, March 25, Fulton and colleague Trent Van Epps sent the board a letter ultimately signed by 53 members of the Protocol group, roughly half of the department. The letter backed the Mandate's direction "but cannot in good faith affirm under these conditions," the complaint says, and stated that the signatories "do not resign."

On March 27, Aue announced he would treat the signatories as committed and conceded that "[i]f I had the opportunity to redo it, I would certainly handle many aspects differently," the complaint says. All 53 signatories kept their jobs. On April 6, Aue fired the only two people who had organized the letter, thirty minutes apart, and refused to tell either of them why, according to the complaint. Van Epps was fired thirty minutes before Fulton.

Aue fired Fulton by video call, the complaint says, telling her that her "track record is good," that she had "broad support among colleagues," and that she had "not been found lacking in any of [her] responsibilities." He then offered to keep paying her salary for a year, so long as she worked somewhere else, the complaint says. Seven months before she was fired, her supervisor had rated her "Greatly exceeding expectations," called her work "pretty much textbook" for her level, and given her a 21.9% raise, according to the complaint. She was never criticized, disciplined, warned or placed on a performance plan, it says.

Fulton facilitated Ethereum's ($ETH) All Core Developers calls, the open process through which the protocol itself is upgraded. She still runs those meetings today, from outside the foundation, because the engineers who build Ethereum ($ETH) kept her on even though the foundation did not, the complaint says. Since 2021 she has also led EthStaker, a nonprofit that teaches members of the public how to help operate the Ethereum ($ETH) network.

The seppuku license and the March 20 ultimatum

The dispute centers on the foundation's Mandate, a statement of direction sent to all staff on February 25, 2026. Its eleventh page reproduced a "Source Seppuku License" pledging that each "author, maintainer, editor or (re)distributor" would "take his or her own life with a sword" upon any failure to uphold its terms, according to the complaint. Seventy-nine employees voted to remove it.

One employee asked management in writing whether signing meant he was required to commit suicide, the complaint says. Another cited a colleague lost to suicide the year before. Aue told staff the pledge was "chosen deliberately, but not meant to be taken literally," Unchained reported, and management updated the form to specify that the commitment had nothing to do with literal seppuku.

On March 5, Buterin told staff the document was "continuing to be worked on with significant changes especially to the areas where people have expressed the most concern or confusion," according to the complaint. The board then published the final Mandate on March 13 with the pledge intact, word for word, the complaint says, now set in a cartoon typeface beside a winking anime figure and cartoon cats, and inscribed permanently on the Ethereum ($ETH) blockchain. The copy posted on the foundation's website, checked by Unchained on November 9, has no searchable instance of "seppuku," though a cartoon on page 11 includes two pledges and the cartoon cat's speech bubble reads, "May the Foundation fall on its own sword if it fails to uphold its solemn promise to Ethereum."

One week later, on Friday, March 20, Aue issued an ultimatum to every employee: personally commit to the Mandate by Monday, or be treated as having resigned, the complaint says. Asked why the default was termination, he wrote: "It has to be default to leaving to ensure that everyone staying make an active commitment." Asked who had agreed to include the suicide pledge, he wrote: "If you are asking more broadly who agreed with including it, I did."

The Mandate itself charted the foundation's role in Ethereum's ($ETH) ongoing development, Cointelegraph reported. It highlighted censorship resistance, open-source code, privacy and security, and said the foundation would focus on protocol upgrades, research and developer tools.

The recorded conversation with Buterin

Three and a half weeks after the firings, Buterin explained the terminations in a recorded conversation with Fulton, the complaint says. Asked how he would regard an organization that fired an employee for organizing immediately after she disclosed a cancer diagnosis, he did not dispute the premise, according to the complaint. He answered that the question was "what kind of dynamics you want to reward inside of the EF," and that "if you reward making a stink with outcomes, then everyone will know that essentially making that kind of a show both internally and externally is the way to cause outcomes inside of the EF."

The complaint presents that exchange as a sitting board member describing the firing of a cancer patient as a deterrent. Buterin participated in the adoption and defense of the Mandate and the ultimatum, received Fulton's written objection, and, on information and belief, approved, ratified or acquiesced in the decision to terminate her, the complaint says.

What the foundation said, and what comes next

That afternoon, April 6, the defendants sent Fulton a release document covering every claim she had, including her claims under the Americans with Disabilities Act and the Family and Medical Leave Act, and told her that if she did not sign it within three days she would be terminated with "no severance or other benefit," the complaint says. Her health insurance was ending in three weeks. Unable to find and retain a lawyer in three days, she signed under duress, received nothing, and rescinded the release through counsel eight days later, according to the complaint.

In a May 14 letter quoted in the complaint, a lawyer for Ethereum Asia Pacific Limited denied that Fulton "was subjected to unlawful conduct, economic duress, retaliation," or "termination in violation of public policy," and said her separation agreement was binding. Cointelegraph reached out to the foundation, Fulton and Van Epps for comment, but had not received a response by publication.

The claims include disability discrimination and retaliation under federal and Colorado law, medical-leave interference and retaliation, and a Colorado aiding-and-abetting claim against Aue and Buterin, Unchained reported. Fulton also seeks liquidated damages, statutory penalties, attorney fees and costs, and a declaration that the separation agreement does not bar her claims and that no agreement requires her to arbitrate them, in Singapore or anywhere else, the complaint says.

As of November 9, the docket showed no filings after November 4, and the foundation, Aue and Buterin had not responded publicly, Unchained reported. The lawsuit concerns employment decisions inside the foundation, not the operation of the Ethereum ($ETH) blockchain, and none of the reporting ties the case to protocol development or to the price of Ether ($ETH).

Sources

• Complaint, Fulton v. Ethereum Asia Pacific Limited et al., Case No. 1:26-cv-05818, filed November 4, 2026, US District Court for the District of Colorado, via CourtListener (primary source: the 55-page complaint and jury demand; the timeline of the March 19 diagnosis, March 24 disclosure, March 25 letter signed by 53 Protocol group members, and April 6 firings thirty minutes apart; the "Source Seppuku License" text and the 79-employee vote to remove it; the March 20 ultimatum and Aue's replies; the "Greatly exceeding expectations" rating and 21.9% raise; the release document, the three-day signing deadline and the rescission eight days later; the recorded conversation with Buterin; the eleven claims and the relief sought, including a declaration on the separation agreement and arbitration)
• Unchained, Fired Employee Sues the Ethereum Foundation and Vitalik Buterin, published November 9, 2026 (secondary reporting: the complaint names six defendants and Buterin is a defendant in five of the eleven claims; the Mandate was sent to staff on February 25; the final version published March 13 kept the pledge text as a small image; the foundation's website copy has no searchable instance of "seppuku"; as of November 9 the docket showed no filings after November 4 and the defendants had not responded publicly; the foundation laid off 54 employees in June)
• Cointelegraph, Ethereum Foundation and Vitalik Buterin Sued Over Firing, published November 10, 2026 (secondary reporting: Fulton alleges she was fired after disclosing a cancer diagnosis and organizing a staff letter; Aue fired Fulton and Van Epps thirty minutes apart on April 6; the foundation published its Mandate in March, highlighting censorship resistance, open-source code, privacy and security; Cointelegraph reached out to the foundation, Fulton and Van Epps for comment and had not received a response by publication)

This article is news reporting and is not investment advice.