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TI-2026-68956 Aliases CVE-2026-81535GHSA-cqr9-f685-gr3w

Missing authorization lets SSH peers open forwarded channels in wolfSSH

Priority LOW 28CWE-862Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
Present
Impact type
Security bypass
Confidentiality · integrity · availability
None · None · Low
Fix status
No fix listed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-862.

Summary

wolfSSH from 1.4.8 through 1.5.0 built with --enable-fwd accepts forwarded-tcpip channel opens without an authorization check and does not cap how many it accepts. A malicious SSH peer can make an endpoint allocate unbounded per-channel buffers for forwarding channels the application never authorized. A malicious server can also open forwarding channels for addresses and ports the client never requested, because the client does not check them against its tcpip-forward registrations (CWE-862).

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Description from the CNA

In wolfSSH through 1.5.0 built with --enable-fwd, DoChannelOpen() in src/internal.c gates only direct-tcpip channel opens with the forwarding policy callback. forwarded-tcpip opens are admitted without an authorization check and are not capped in number, allowing a malicious SSH peer to make an endpoint allocate unbounded per-channel buffers for forwarding channels the application never authorized. A client also does not check a forwarded-tcpip open against the forwards it registered with a tcpip-forward request, as RFC 4254 section 7.2 requires, so a malicious server can open forwarding channels for addresses and ports the client never asked it to forward.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00305 23rd percentileScored 2026-11-07
Fix No fix listed No fixed version in the sources yet

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
wolfSSLwolfSSH1.4.8 – 1.5.0—No fix listedCNA
  • wolfSSH VendorwolfSSL Affected 1.4.8 – 1.5.0 Fixed in — No fix listed CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:wolfssh:wolfssh:*:*:*:*:*:*:*:*before 1.6.0VulnerablewolfSSH
  • cpe:2.3:a:wolfssh:wolfssh:*:*:*:*:*:*:*:* Versions before 1.6.0 Vulnerable ·wolfSSH

Remediation

The sources list no fixed version for wolfSSH.

Written with Claude Haiku 5.5 from the sources below · 2026-10-29

Timeline

  1. 2026-10-07 Threatist record created from CVE-2026-81535
  2. 2026-10-07 Alias added: GHSA-cqr9-f685-gr3w
  3. 2026-10-07 CISA SSVC decision points changed
  4. 2026-10-07 Priority changed: MEDIUM → LOW
  5. 2026-10-13 CVSS score added · NVD

References

Patch 3

  • TI-2024-00830 SEGV and out of bounds memory read from malicious packet CVSS 3.1CRITICAL 9.1
  • TI-2009-04246 Multiple stack-based buffer overflows in the CertDecoder::GetName function in src/asn.cpp… CVSS 2.0HIGH 7.5
  • TI-2022-18557 In wolfSSL before 5.5.1, malicious clients can cause a buffer overflow during a TLS 1.3… CVSS 3.1HIGH 7.5
  • TI-2025-10943 Potential DoS Vulnerability through Multiple KeyShareEntry with Same Group in TLS 1.3 ClientHello CVSS 4.0MEDIUM 6.3
  • TI-2017-09737 wolfSSL Bleichenbacher/ROBOT CVSS 3.0HIGH 7.5
  • TI-2019-08902 wolfSSL 4.0.0 has a Buffer Overflow in DoPreSharedKeys in tls13.c when a current identity… CVSS 3.1CRITICAL 9.8
See all 176 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences