# CVE-2026-62642: Roundcube Webmail infinite loop in TNEF decoder

Source: https://junglewise.ai/threats/cve-2026-62642-roundcube-webmail-infinite-loop-in-tnef-decoder  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-07-14. Updated: 2026-07-14  
License: CC BY 4.0 with a link back

CVE-2026-62642 · Severity: medium · CVSS 4.3 · Published 2026-07-14

Roundcube Webmail, a widely used browser-based email client, is vulnerable to a denial-of-service attack. An attacker can send a specially crafted email with a TNEF (winmail.dat) attachment that, when opened by a user, causes the mail server to enter an infinite loop. This can lead to service instability or unavailability for the affected user or the entire webmail instance.

Technologies: [Roundcube Webmail](https://junglewise.ai/threats/technologies/webmail). Vendors: [Roundcube](https://junglewise.ai/threats/vendors/roundcube).

## Quick answers

**Is CVE-2026-62642 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-62642 being exploited in the wild.

**How severe is CVE-2026-62642?** Medium severity, with a CVSS score of 4.3, published 14 July 2026.

**Which products and versions are affected?** Roundcube Webmail before 1.6.17, 1.7.x before 1.7.2.

**Is there a fix for CVE-2026-62642?** A patch was published on 2026-07-05: Security updates 1.6.17 and 1.7.2 released by vendor. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-62642 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-62642?** Check whether you run Roundcube Webmail 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.

## Technical details

A vulnerability classified as CWE-835 (Loop with Unreachable Exit Condition) exists in the TNEF (winmail.dat) decoder of Roundcube Webmail. The flaw is located in the rcube_tnef_decoder.php component. An unauthenticated remote attacker can exploit this by sending an email containing a malformed TNEF attachment. When a user attempts to view the email, the decoder enters an infinite loop, consuming system resources and resulting in a Denial of Service (DoS). The issue is addressed in versions 1.6.17 and 1.7.2.

## Affected products

- Roundcube Webmail before 1.6.17, 1.7.x before 1.7.2

## Timeline

- 2026-07-05: patched: Security updates 1.6.17 and 1.7.2 released by vendor.
- 2026-07-14: advisory: CVE published to NVD.

## References

- [https://github.com/roundcube/roundcubemail/commit/132ac8dd5a55c8466be12de1daf84355697ffa89](https://github.com/roundcube/roundcubemail/commit/132ac8dd5a55c8466be12de1daf84355697ffa89)
- [https://github.com/roundcube/roundcubemail/commit/877269c79359d959a94f13c9070cab0f3389c193](https://github.com/roundcube/roundcubemail/commit/877269c79359d959a94f13c9070cab0f3389c193)
- [https://github.com/roundcube/roundcubemail/commit/a007321346380136b3de2bd75b486b04f63c0d38](https://github.com/roundcube/roundcubemail/commit/a007321346380136b3de2bd75b486b04f63c0d38)
- [https://github.com/roundcube/roundcubemail/commit/fb952956c6eaf29e963f1a718d028d66e7957ce0](https://github.com/roundcube/roundcubemail/commit/fb952956c6eaf29e963f1a718d028d66e7957ce0)
- [https://github.com/roundcube/roundcubemail/releases/tag/1.6.17](https://github.com/roundcube/roundcubemail/releases/tag/1.6.17)
- [https://github.com/roundcube/roundcubemail/releases/tag/1.7.2](https://github.com/roundcube/roundcubemail/releases/tag/1.7.2)
- [https://roundcube.net/news/2026/07/05/security-updates-1.6.17-and-1.7.2](https://roundcube.net/news/2026/07/05/security-updates-1.6.17-and-1.7.2)

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