High Authentication

CVE-2026-56837 — PraisonAI LinearBot processes unsigned webhooks when LINEAR_WEBHOOK_SECRET is missing

PraisonAI is a multi-agent teams system. From version 4.6.56 to before version 4.6.59, PraisonAI's LinearBot starts a public webhook listener on 0.0.0.0 and treats LINEAR_WEBHOOK_SECRET as optional. When the secret is absent, startup only logs a warning and _handle_webhook() skips Linear-Signature verification entirely. An unauthenticated network caller who can reach the webhook endpoint can submit a forged Linear-Event: AgentSession request. The forged request is parsed, scheduled for background processing, dispatched to _handle_agent_session(), and passed into BotSessionManager.chat(). The bot then attempts to post the agent response back to Linear under the configured bot token. The PoV is offline and deterministic. It does not contact Linear. It calls the webhook handler directly, monkey-patches the outbound Linear comment path, and proves both sides of the boundary. This issue has been patched in version 4.6.59.

Published Oct 23, 2026 · Updated Oct 23, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: GitHub_M

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+1
Technical severity (high)+6
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.19%

ahead of 8% of scored CVEs · Oct 29, 2026

Affects

MervinPraison

PraisonAI and 1 more

CVSS base

8.6

High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

Pip Praisonai: fixed in version 4.6.59 — github.com (GitHub Security Advisories)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (MervinPraison PraisonAI, Pip Praisonai).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
Apply the fixed version or the patch documented under Remediation.
Search available logs for exploit probes matching the vulnerability class (authentication), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
MervinPraison	PraisonAI	version >= 4.6.56, < 4.6.59	Vulnerable	CVE Program (cve.org) e CISA ADP
Pip	Praisonai	≥ 4.6.56 and ≤ 4.6.58	Vulnerable	GitHub Security Advisories

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

High

Availability

Low

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
8.6	CVSS 3.1	High	3.9	4.7	security-advisories@github.com via NIST National Vulnerability Database
8.6	CVSS 3.1	High	—	—	GitHub, Inc. via GitHub Security Advisories
8.6	CVSS 3.1	High	—	—	GitHub_M via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L (score shown at the top: security-advisories@github.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-287 · Improper Authentication

Other CVEs with this weakness →

EPSS over time FIRST

Oct 24, 2026 → Oct 29, 2026 · 6 reading(s) · max 0.25%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Review authentication logs: logins without MFA, anomalous sessions and recently created accounts.

web/proxy/WAF logsnetwork IDS/IPSauthentication logs

Timeline

What happened to this CVE, newest first.

2026
SSVC assessment updated
Oct 23, 2026 · CVE Program (cve.org) e CISA ADP
Fix documented
Oct 23, 2026 · GitHub Security Advisories
Affected products added · pip/praisonai
Oct 23, 2026 · GitHub Security Advisories
Affected products added · mervinpraison/praisonai
Oct 23, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 23, 2026
CVSS changed · 8.6
Oct 23, 2026 · NIST National Vulnerability Database
Source status changed · → Deferred
Oct 23, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 23, 2026 · Alertas do Telegram
CVE published
Oct 23, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

2× References added · Oct 23, 2026 – Oct 23, 2026
1× Official description updated · Oct 23, 2026 – Oct 23, 2026

References

2 on the record

github.com/advisories/GHSA-fc26-m9pf-v56q
GitHub Security Advisories
github.com/MervinPraison/PraisonAI/security/advisories/GHSA-fc26-m9pf-v56q
x_refsource_CONFIRM, NIST National Vulnerability Database

Elsewhere on this site

MervinPraison
every CVE for this vendor

Authentication
same class

CWE-287
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-57144 PraisonAI SandlockSandbox falls back to unrestricted subprocess execution when Landlock is unavailable 7d
High CVE-2026-57121 PraisonAI: Missing ownership check on DELETE endpoints allows members to delete others' content in Platform API 7d
High CVE-2026-57142 PraisonAI recipe workflow policy can be bypassed by declaring and YAML-approving dangerous tools outside TEMPLATE.yaml 7d
High CVE-2026-57146 PraisonAI A2U incomplete authentication fix leaves current serve command unauthenticated by default 7d
High CVE-2026-57114 PraisonAI: Jobs webhook SSRF protection bypass via DNS rebinding 7d
High CVE-2026-57117 PraisonAI: Compute-bridged file tools allow shell command injection 7d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-56837 is "PraisonAI LinearBot processes unsigned webhooks when LINEAR_WEBHOOK_SECRET is missing", rated High. It affects PraisonAI (MervinPraison); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.6 describes technical severity. EPSS 0.19% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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