CVE-2026-11443VulnerabilityPublished 11 Jun 2026

ZDI-26-358: Allegra downloadAttachment Cross-Site Scripting Authentication Bypass Vulnerability

Source Zero Day Initiative

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Not known to be exploited.

Data as of 30 Oct 2026, 06:59 UTC

Severity

Medium

Rated Medium by Zero Day Initiative · No CVSS score from NVD or the CNA

EPSS: 0.8% chance of exploitation in 30 days – higher than 57% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

Disclosed: evidence found.
Public on cve.org; its publication date is not in this record
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

remote

What to do

AI-suggested

Allegra has issued an official update that corrects this vulnerability. Users and administrators should apply the update as described in Allegra's release notes for version 9.0.0 to remediate this issue. No additional mitigation steps are indicated by the vendor advisory.

Description

This vulnerability allows remote attackers to execute arbitrary script on affected installations of Allegra. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file. The ZDI has assigned a CVSS rating of 4.6. The following CVEs are assigned: CVE-2026-11443.

Impact

Successful exploitation allows remote attackers to execute arbitrary scripts within the context of the affected user's session, potentially leading to information disclosure or session hijacking. The vulnerability requires user interaction and has a CVSS base score of 4.6, reflecting limited impact and exploit complexity.

Summary

The Allegra downloadAttachment method improperly validates user-supplied data, enabling remote attackers to inject and execute arbitrary scripts in the context of the current user. Exploitation requires user interaction, such as visiting a malicious webpage or opening a malicious file. This vulnerability is tracked as CVE-2026-11443 and was publicly disclosed by the Zero Day Initiative on June 11, 2026. Allegra has released an update to fix this issue as detailed in their release notes for version 9.0.0.

References

zerodayinitiative.com/advisories/ZDI-26-358/ (opens in a new tab)

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