VulnerabilityPublished 26 May 2026

CVE-2026-44843: langchain · Deserialization of Untrusted Data

Affects langchainSource CVE Database V5

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Not known to be exploited · CVSS 8.2 High : upgrade to 1.3.3 or 0.3.85 soon.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score

8.2High

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.
Patch: Available – fixed in 1.3.3, 0.3.85

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

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

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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact on the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 26 May 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 30 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

Upgrade langchain to 1.3.3 or 0.3.85; langchain to 0.3.85.

Affected software

Product	Affected	Fixed in
langchain-ailangchain	Affected >=1.0.0a1 <1.3.3	Fixed in 1.3.3
langchain-ailangchain	Affected <0.3.85	Fixed in 0.3.85
PyPIlangchain`pkg:pypi/langchain`Other threats	Affected <0.3.85	Fixed in 0.3.85

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

AI-suggested

Upgrading LangChain to version 0.3.85 or later, or 1.3.3 or later, fully addresses this vulnerability. No other official remediation or temporary fixes are documented. Users should apply these updates to ensure the vulnerability is mitigated.

Description

LangChain versions prior to 0.3.85 and between 1.0.0a1 and before 1.3.3 contain a deserialization vulnerability. The framework uses overly broad allowlists when deserializing certain runtime inputs, allowing trusted LangChain-serializable objects to be instantiated with untrusted constructor arguments. This can lead to unintended object instantiation during deserialization. The vulnerability is identified as CWE-502 and has a high severity with a CVSS score of 8.

Impact

Successful exploitation could allow an attacker to supply crafted serialized data that causes the application to instantiate objects with untrusted constructor arguments. This may lead to unauthorized information disclosure (high confidentiality impact) and limited integrity impact. There is no reported impact on availability. No known exploits are currently reported in the wild.

Summary

LangChain is affected by a deserialization of untrusted data vulnerability (CWE-502) in versions prior to 0.3.85 and from 1.0.0a1 up to but not including 1.3.3. The issue arises because certain runtime code paths deserialize inputs using an overly broad allowlist, specifically calling load() with allowed_objects="all". While this does not permit arbitrary Python object deserialization, it allows any trusted LangChain-serializable object to be revived, which is broader than necessary. Consequently, attacker-supplied serialized constructor dictionaries may cause trusted runtime paths to instantiate classes with untrusted constructor arguments. This vulnerability is addressed by updates in versions 0.3.85 and 1.3.3.

CWE-502Deserialization of Untrusted Data (opens in a new tab)
Base weaknessLikelihood of exploit: MediumCWE Top 25 (2025): #15OWASP Top 10 A08:2025: Software or Data Integrity Failures (opens in a new tab)
The product deserializes untrusted data without sufficiently ensuring that the resulting data will be valid.
Architecture and Design · Implementation
If available, use the signing/sealing features of the programming language to assure that deserialized data has not been tainted. For example, a hash-based message authentication code (HMAC) could be used to ensure that data has not been modified.
Implementation
When deserializing data, populate a new object rather than just deserializing. The result is that the data flows through safe input validation and that the functions are safe.
Implementation
Explicitly define a final object() to prevent deserialization.
OWASP Cheat Sheets
Abuse Case (opens in a new tab)
Deserialization (opens in a new tab)
XML Security (opens in a new tab)
XML External Entity Prevention (opens in a new tab)
Software Supply Chain Security (opens in a new tab)
OWASP ASVS 4.0.3
V1.5.2 (opens in a new tab)
V5.5.3 (opens in a new tab)
V5.5.1 (opens in a new tab)
Attack patterns
Object Injection (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/langchain-ai/langchain/security/advisories/GHSA-pjwx-r37v-7724 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 2 Jun 2026, 21:17 UTC

WeaknessesCWE-502

Technical details

References

Community reviews

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