CVE Intelligence
Medium Info disclosure

CVE-2026-105963 — Secret key base exposed in stack trace arguments on wrong-typed Plug.Crypto arguments

Externally-Generated Error Message Containing Sensitive Information vulnerability in plug_crypto in elixir-plug plug_crypto allows an unauthenticated remote attacker to expose the secret key base through application logs via a wrong-typed argument. Every public function in Plug.Crypto validates argument types in a function-head guard. A failed guard makes the Erlang VM raise FunctionClauseError with the actual argument values in the top stack frame, so the secret key base, a derived key, or the value an API key is compared against lands in that frame. The library's rescue blocks and Plug.Crypto.prune_args_from_stacktrace/1 only reach exceptions raised inside a function body, so they never see a guard failure. Plug.Cowboy and Bandit write the frame to the error log and attach it as crash_reason Logger metadata, which error trackers forward. Two entry points take request data. Plug.Crypto.verify/4 exposes the secret key base when the token is neither a binary nor nil, which Phoenix.Token.verify/4 reaches because it forwards the token unguarded. Plug.Crypto.secure_compare/2 exposes the other operand when one side is not a binary, as happens when a missing request header yields nil. Reading the leaked value needs separate access to the logs or the error tracker, so the request alone does not disclose the secret to the attacker. This issue affects plug: from 1.6.3 before 1.7.0; plug_crypto: from 1.0.0 before 2.2.1.

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

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 0.5% (30-day exploitation probability)+7
  • Technical severity (medium)+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
0.51%
ahead of 43% of scored CVEs · Oct 30, 2026
Affects
Elixir-plug
Plug and 1 more
CVSS base
5.1
Medium · 2 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
No
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.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

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.

  1. Identify exposed assets running the affected vendor/product/version combinations (Elixir-plug Plug, Elixir-plug Plug Crypto).
  2. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  3. Search available logs for exploit probes matching the vulnerability class (info disclosure), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Elixir-plug Plug ≥ 1.6.3 and < 1.7.0≥ 56000c33d8a0a2fbac491f8be06b9c5112bc2276 Vulnerable CVE Program (cve.org) e CISA ADP
Elixir-plug Plug Crypto ≥ 1.0.0 and < 2.2.1≥ 2d078b7b8264c565f0ff71235c515f4f46882dcf and < 981887493dada0fce7003c61861c00dfbb0fc8c5 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

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

Attack vector
Network
Attack complexity
Low
Attack requirements
None
Privileges required
High
User interaction
None
Scope
X
Confidentiality (vulnerable system)
Low
Integrity (vulnerable system)
None
Availability (vulnerable system)
None
Confidentiality (subsequent)
None
Integrity (subsequent)
None
Availability (subsequent)
None

Every base score collected

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

ScoreVersionSeverityExpl.ImpactScored by
5.1 CVSS 4.0 Medium — — 6b3ad84c-e1a6-4bf7-a703-f496b71e49db via NIST National Vulnerability Database
5.1 CVSS 4.0 Medium — — EEF via CVE Program (cve.org) e CISA ADP
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/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 (score shown at the top: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-532 · Insertion of Sensitive Information into Log File

Other CVEs with this weakness →

EPSS over time FIRST

Oct 23, 2026 → Oct 30, 2026 · 8 reading(s) · max 0.72%

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).
  • Look for anomalous data read/export volumes and access to sensitive records.
web/proxy/WAF logsnetwork IDS/IPSapplication logsauthentication logs

Timeline

What happened to this CVE, newest first.

  • 2026
  • Source status changed · Received → Deferred
    Oct 23, 2026 · NIST National Vulnerability Database
  • SSVC assessment updated
    Oct 23, 2026 · CVE Program (cve.org) e CISA ADP
  • Affected products added · elixir-plug/plug, elixir-plug/plug crypto
    Oct 23, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 23, 2026
  • CVSS changed · 5.1
    Oct 23, 2026 · NIST National Vulnerability Database
  • Source status changed · → Received
    Oct 23, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 23, 2026 · Alertas do Telegram
  • CVE published
    Oct 23, 2026 · EEF

Source activity

Repeated readings are counted rather than listed.

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

References

7 on the record

Elsewhere on this site

Elixir-plug
every CVE for this vendor
Info disclosure
same class
CWE-532
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-56813 Cookie attribute injection in Plug.Conn.Cookies.encode/2 Jul 10, 2026
  • CVE-2026-56814 Plug: multipart :length limit is not charged for part headers, enabling unbounded temp-file creation (denial of service) Jul 10, 2026
  • CVE-2026-54892 Plug: quadratic-time decoding of nested query/body parameters enables denial of service Jun 23, 2026
  • CVE-2026-8468 Unbounded buffer accumulation in multipart header parsing causes denial of service in plug May 14, 2026

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 fixed version, patch or mitigation documented.
  • 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-2026-105963 is "Secret key base exposed in stack trace arguments on wrong-typed Plug.Crypto arguments", rated Medium. It affects Plug (Elixir-plug); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.1 describes technical severity. EPSS 0.51% 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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