# CitrixBleed 2: NetScaler memory leak exploited to hijack sessions · pwn.watch

> An out-of-bounds read in NetScaler ADC and Gateway leaked memory, including session tokens, to unauthenticated attackers. GreyNoise saw exploitation from June 23, before public PoCs on July 4. After patching, admins had to kill all active ICA, PCoIP, RDP, AAA and LB sessions.

Page: https://pwn.watch/i/citrixbleed-2-netscaler-cve-2025-5777 · generated 2026-10-23T03:01:01.167Z

## Status
- Severity: critical · status: closed · patch: patched
- Product: Citrix NetScaler ADC and Gateway
- Started: 2025-06-17 · closed: 2025-07-10
- CVEs: CVE-2025-5777
- Affected: See Citrix bulletin
- Fixed in: 14.1-43.56; 13.1-58.32; 13.1-FIPS/NDcPP 13.1-37.235

## Follow this incident
- RSS (one item per update): https://pwn.watch/i/citrixbleed-2-netscaler-cve-2025-5777/feed.xml
- JSON Feed: https://pwn.watch/i/citrixbleed-2-netscaler-cve-2025-5777/feed.json
- Full data (timeline, sources, posts, agentBrief): https://pwn.watch/i/citrixbleed-2-netscaler-cve-2025-5777.json
- This file: https://pwn.watch/i/citrixbleed-2-netscaler-cve-2025-5777/llms.txt

## Updates (newest first)
- 2025-07-10: CISA adds CVE-2025-5777 to KEV
- 2025-07-04: watchTowr publishes technical analysis; public PoCs follow (https://labs.watchtowr.com/how-much-more-must-we-bleed-citrix-netscaler-memory-disclosure-citrixbleed-2-cve-2025-5777/)
- 2025-06-26: ReliaQuest reports likely targeted exploitation (https://reliaquest.com/blog/threat-spotlight-citrix-bleed-2-vulnerability-in-netscaler-adc-gateway-devices/)
- 2025-06-23: GreyNoise observes exploitation starting (https://www.greynoise.io/blog/exploitation-citrixbleed-2-cve-2025-5777-before-public-poc)
- 2025-06-17: Citrix discloses CVE-2025-5777 and releases fixes

## Fix brief
# Security brief: CitrixBleed 2: NetScaler memory leak exploited to hijack sessions

Source: https://pwn.watch/i/citrixbleed-2-netscaler-cve-2025-5777 · status: closed (closed Jul 10, 2025) · severity: critical · updated Jul 10, 2025

## Patch status
**PATCHED: fixed releases exist. Upgrade to a fixed version.**

## What it is
An out-of-bounds read in NetScaler ADC and Gateway leaked memory, including session tokens, to unauthenticated attackers. GreyNoise saw exploitation from June 23, before public PoCs on July 4. After patching, admins had to kill all active ICA, PCoIP, RDP, AAA and LB sessions.

Severity detail: Pre-auth memory disclosure, session hijack; CISA KEV; known ransomware use

- Product: Citrix NetScaler ADC and Gateway
- CVE / advisory ids: CVE-2025-5777

## Affected versions
- See Citrix bulletin

## Check whether you're affected
No generic command applies (the product is a hosted service, appliance or desktop app). Check the installed version in its admin UI / About screen and compare with the versions above.

## Fix
Upgrade to one of these fixed versions (or later on the same branch):
- 14.1-43.56
- 13.1-58.32
- 13.1-FIPS/NDcPP 13.1-37.235

After upgrading, re-run the checks above and redeploy/restart the affected services.

## Secrets to rotate
This incident involves possible credential exposure. Rotate any credentials (API keys, tokens, env vars, SSH keys) that were present on affected systems or in affected builds while vulnerable/compromised versions were installed, and review access logs.

## Latest updates
- Jul 10, 2025: CISA adds CVE-2025-5777 to KEV
- Jul 4, 2025: watchTowr publishes technical analysis; public PoCs follow
- Jun 26, 2025: ReliaQuest reports likely targeted exploitation
- Jun 23, 2025: GreyNoise observes exploitation starting
- Jun 17, 2025: Citrix discloses CVE-2025-5777 and releases fixes

## Advisories
- [NVD: CVE-2025-5777](https://nvd.nist.gov/vuln/detail/CVE-2025-5777) (NVD)
- [CISA Known Exploited Vulnerabilities Catalog](https://www.cisa.gov/known-exploited-vulnerabilities-catalog) (CISA)

## Write-ups & news
- [CVE-2025-5777: Citrix Bleed 2 Opens Old Wounds](https://reliaquest.com/blog/threat-spotlight-citrix-bleed-2-vulnerability-in-netscaler-adc-gateway-devices/)
- [Exploitation of CitrixBleed 2 Began Before PoC Was Public](https://www.greynoise.io/blog/exploitation-citrixbleed-2-cve-2025-5777-before-public-poc)
- [How Much More Must We Bleed? (CitrixBleed 2)](https://labs.watchtowr.com/how-much-more-must-we-bleed-citrix-netscaler-memory-disclosure-citrixbleed-2-cve-2025-5777/)

## Caveats
Fixed builds as summarized by ReliaQuest/SecurityWeek from the Citrix bulletin; confirm against the Citrix bulletin.

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Machine-readable: https://pwn.watch/i/citrixbleed-2-netscaler-cve-2025-5777.json · all incidents: https://pwn.watch/incidents.json. Verify against the vendor advisory before changing production systems.