VulnerabilityPublished 24 Apr 2026

CVE-2026-33662: OP-TEE optee_os · Integer Overflow or Wraparound

Affects OP-TEE optee_osSource CVE Database V5

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Not known to be exploited · CVSS 7.5 High.

Data as of 30 Oct 2026, 06:59 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 34% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
OP-TEEoptee_os	Affected >=3.8.0 <=4.10	Fixed in–
GitHubop-tee/optee_os`pkg:github/op-tee/optee_os`Other threats	Affected =3.8.0 <=4.10	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Until an official fix is available, users should consider avoiding configurations with small RSA modulus sizes that could trigger the overflow or disabling RSA acceleration if feasible. Monitor vendor channels for updates and apply patches once released.

Description

CVE-2026-33662 is an integer overflow vulnerability in the OP-TEE optee_os versions 3.8.0 through 4.10. It occurs in the emsa_pkcs1_v1_5_encode() function when calculating padding size for RSA keys with small modulus values, leading to an underflow. This causes a memset() call to overwrite memory beyond intended bounds, resulting in a crash of OP-TEE. The issue affects only platforms that register RSA acceleration. The vulnerability has a CVSS score of 7.5 and is classified as high severity due to its potential to cause denial of service by crashing the trusted execution environment. No official patch or remediation guidance is currently provided by the vendor, and no known exploits are reported in the wild.

Impact

The integer overflow causes memory corruption that leads to a denial of service by crashing the OP-TEE trusted execution environment. There is no indication of confidentiality or integrity impact, only availability is affected. This could disrupt secure operations relying on OP-TEE on affected platforms, particularly those using RSA acceleration.

Summary

The vulnerability exists in OP-TEE's optee_os component, specifically in the emsa_pkcs1_v1_5_encode() function used for RSA signature padding. The calculation of the padding size (PS size) subtracts the digest size and other encoding fields from the RSA modulus size. If the modulus is small enough, this subtraction results in an integer underflow (wraparound), causing the padding size to become a very large number. Consequently, the memset() function writes 0xFF bytes beyond the intended buffer, leading to memory corruption and a crash of the OP-TEE environment. This flaw affects versions from 3.8.0 up to 4.10 and only impacts platforms that enable RSA acceleration. The vulnerability is tracked as CWE-190 (Integer Overflow or Wraparound) and has a CVSS 3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

CWE-190Integer Overflow or Wraparound (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
Requirements
Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V5.4.3 (opens in a new tab)
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
Attack patterns
Forced Integer Overflow (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/OP-TEE/optee_os/security/advisories/GHSA-4cf8-v5g3-73gr (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 1 May 2026, 20:41 UTC

WeaknessesCWE-190

Technical details

References

Community reviews

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