Zammad: Missing rate limiting allows password brute-forcing during two-factor login

published 2026-09-25 44 d ago modified 2026-09-28 41 d ago also EUVD-2026-87267

cvss: 6.9; version 4.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.3%; EPSS 0.3% chance of exploitation in 30 days, percentile 25%
public exploits: 0; none known

Zammad is a web based open source helpdesk/customer support system. Prior to 7.1.2, the two-factor login step let an attacker try unlimited password guesses for any account without triggering Zammad's normal lockout or rate limiting. The response also revealed whether a guess was correct, even before two-factor authentication was checked. This made it possible to brute-force weak or reused passwords. This issue is fixed in version 7.1.2.

Patch / fix

links 1

github.com/zammad/zammad@d51254f commit

CISA SSVC

Exploitation: none
Automatable: yes
Technical impact: partial
Assessed: 44 d ago (2026-09-25)

Exploit prediction

0.32% chance of exploitation in the next 30 days, higher than 25% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	4.0	6.9	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
CNA	4.0	6.9	CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Affected products

zammad zammad

Classification

Weakness

CWE-203 Observable Discrepancy
CWE-307 Improper Restriction of Excessive Authentication Attempts
CWE-799 Improper Control of Interaction Frequency

References

Sources

CVE List CVE-2026-84461
NVD CVE-2026-84461

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary