Certificate authority eMudhra has revoked eight compromised intermediate certificates after researchers discovered their private keys were trivially recoverable, a flaw that could have let attackers forge trusted TLS certificates for any website and intercept encrypted traffic.
A security researcher known as Wayne found the issue on October 17 while scanning publicly available certificate data. According to Mozilla’s incident report, all eight certificates relied on P-384 private keys generated in April 2025 with values smaller than 256, meaning an attacker only needed to test 256 possible numbers to recover a working key. Researcher Flüpke later published one of the compromised keys on GitHub to demonstrate the flaw, showing the private key for eMudhra’s “EM OV TLS CA – G3C” certificate had a value of just 4. BleepingComputer independently verified the published key matched one of the revoked certificates.
eMudhra told Mozilla the root cause was an error in a script used to generate certificates in April 2025. The bug produced a second set of weak keys that were mistakenly selected for signing because their labels resembled those of properly generated keys. Some of the affected certificates were also submitted to Sectigo for cross-signing.
eMudhra said most of the affected intermediates were never used in production and that it found no evidence they issued certificates to end users. However, the company acknowledged attackers could have recovered and abused the weak keys at any point since April 2025, though there is no evidence this occurred. eMudhra has revoked the eight certificates and halted new issuance under its G3 root.
Browser and ecosystem response
Mozilla blocked the compromised certificates via Firefox’s OneCRL system on October 17, protecting users without requiring an update or restart. Chrome blocked the six compromised intermediates authorized for TLS issuance the same day, and Apple added protections on October 19. Mozilla also shipped Firefox 158.0.1 and ESR updates on October 20 for users whose configurations missed the earlier revocation.
Software that maintains its own certificate store or doesn’t check revocations may still trust the compromised intermediates until patched. The Go team released versions 1.27.3 and 1.26.10 to address the issue, tracked as CVE-2026-111943. Mozilla engineer Dennis Jackson published an incident tracking site listing fixes across Ubuntu, Debian, Arch, Gentoo, FreeBSD, Alpine, NSS, curl, Homebrew, Node.js, Python, Rust crates, Electron, Bun, Composer, and Elixir, with several still pending. Jackson warned that macOS’s built-in curl utility may keep trusting the compromised certificates because its bundle doesn’t check revocation status.
Administrators should consult the advisory’s test endpoints and apply available updates promptly to ensure the compromised certificates are no longer trusted.
