CVE-2026-3055
Insufficient input validation in NetScaler ADC and NetScaler Gateway when configured as a SAML IDP leading to memory overread
Critical
Known exploited
- Severity
- 9.3 / 10
- Critical · CVSS 4.0
- Exploit chance (EPSS)
- 91.49%
- Chance of exploitation in the next 30 days. Higher than 99.81% of scored vulnerabilities.
- Known exploited
- Yes
- In CISA's catalog since Mar 30, 2026
- Weakness
- CWE-125 Out-of-bounds Read
- Fix
- None yet
- No fixed version published
Exploited in the wild. Citrix NetScaler Out-of-Bounds Read Vulnerability (Citrix NetScaler). Required action: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Due for U.S. federal agencies by Apr 2, 2026.
Description
Insufficient input validation in NetScaler ADC and NetScaler Gateway when configured as a SAML IDP leading to memory overread
How to fix
No fixed version has been published yet. Until one is, remove or replace the package, or turn off or isolate the affected feature. This page updates when a fix ships.
Severity breakdown
CVSS 4.0 9.3
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- None
- Privileges required
- None
- User interaction
- None
- Confidentiality (vulnerable system)
- High
- Integrity (vulnerable system)
- High
- Availability (vulnerable system)
- High
- Confidentiality (subsequent systems)
- Low
- Integrity (subsequent systems)
- Low
- Availability (subsequent systems)
- Low
- Exploit maturity
- Not defined
- Scope
- X
CVSS 3.1 9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Weakness
CWE-125: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How to prevent it
- Implementation: Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does. When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue." Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright. To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.
- Architecture and Design: Use a language that provides appropriate memory abstractions.
References
Advisories
Other links
Timeline
- Published
- Added to CISA's Known Exploited Vulnerabilities catalog
- Remediation due for U.S. federal agencies
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-9v9v-9qvf-h2hj Pillow: Heap over-read in WMF/EMF rendering via 16-bit dimension truncation (Windows builds) | High | Same weakness, CWE-125 |
| GHSA-v9pv-5gc8-w2m6 Pillow multi-frame loaders can reuse stale native image storage after mode transitions | Critical | Same weakness, CWE-125 |
| GHSA-h3v5-h239-pg29 Electron: Off-screen rendering on macOS trusts GPU-supplied frame geometry | Low | Same weakness, CWE-125 |
| GHSA-3qxv-5xgr-q7w9 Electron: Frame subscription trusts GPU-supplied frame geometry | Low | Same weakness, CWE-125 |
| GHSA-pchr-8j38-3x4p Pillow: TIFF encoder ColorMap plane-size mismatch causes a heap out-of-bounds read | High | Same weakness, CWE-125 |
| GHSA-c6hw-5grf-ff96 Pillow: OOB read in TiffDecode.c tile and RGBA paths leaks heap memory into pixels | High | Same weakness, CWE-125 |
| GHSA-f8qh-mqg4-9939 Microsoft Security Advisory CVE-2026-96232 - .NET and Visual Studio Information Disclosure Vulnerability | High | Same weakness, CWE-125 |
| GHSA-26w7-cxv4-gfx2 Astro: Remote code execution through AVIF image optimization | Critical | Same weakness, CWE-125 |
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