# CVE-2026-127135: SOGo Sieve script injection in notification address

Source: https://junglewise.ai/threats/cve-2026-127135-sogo-before-5-12-13-contains-a-sieve-script-injection  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-12. Updated: 2026-11-12  
License: CC BY 4.0 with a link back

CVE-2026-127135 · Severity: medium · CVSS 4.3 · Published 2026-11-12

SOGo is a messaging and collaboration server that handles email, calendar, and contacts. A vulnerability in versions before 5.12.13 allows authenticated users to inject malicious Sieve mail filtering directives by manipulating notification settings, enabling attackers to redirect or discard incoming emails and bypass administrator-configured forwarding restrictions.

Technologies: [Alinto Sogo](https://junglewise.ai/threats/technologies/sogo). Vendors: [Alinto](https://junglewise.ai/threats/vendors/alinto).

## Quick answers

**Is CVE-2026-127135 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-127135 being exploited in the wild.

**How severe is CVE-2026-127135?** Medium severity, with a CVSS score of 4.3, published 12 November 2026.

**Which products and versions are affected?** Alinto Sogo before 5.12.13.

**Is there a fix for CVE-2026-127135?** Yes: fixed in SOGo 5.12.13. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-127135 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-127135?** Check whether you run Alinto Sogo at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in SOGo 5.12.13

## Technical details

The vulnerability is a static code injection (CWE-96) in Sieve script generation, where notificationAddress preference values are not properly escaped before being embedded into Sieve scripts. An authenticated attacker can insert Sieve redirect or discard statements to bypass forwarding-domain constraints and manipulate mail delivery. The attack requires prior authentication but no additional user interaction.

## Affected products

- Alinto SOGo before 5.12.13

## Timeline

- 2026-11-12: disclosed
- 2026-11-04: patched: Release SOGo 5.12.13

## References

- [https://github.com/Alinto/sogo/releases/tag/SOGo-5.12.13](https://github.com/Alinto/sogo/releases/tag/SOGo-5.12.13)
- [https://www.vulncheck.com/advisories/sogo-before-sieve-script-injection-via-notification-address](https://www.vulncheck.com/advisories/sogo-before-sieve-script-injection-via-notification-address)

## Related threats

- [SOGo server-side request forgery in Calendar web subscription](https://junglewise.ai/threats/cve-2026-127145-sogo-before-5-12-13-contains-a-server-side-request-forgery)
- [SOGo denial of service via IMAP greeting timeout](https://junglewise.ai/threats/cve-2026-127141-sogo-before-5-12-13-contains-a-denial-of-service-vulnerability)
- [SOGo missing rate limiting in TOTP verification](https://junglewise.ai/threats/cve-2026-127131-sogo-before-5-12-13-contains-a-missing-rate-limiting)
- [SOGo improper cryptographic signature verification in S/MIME](https://junglewise.ai/threats/cve-2026-127121-sogo-before-5-12-13-contains-an-improper-cryptographic-signature)
- [SOGo improper restriction of excessive authentication attempts](https://junglewise.ai/threats/cve-2026-127111-sogo-before-5-12-13-contains-an-improper-restriction-of)