CVE-2026-54887
DTLS server cookie bypass during startup window due to empty initial cookie secret
Description
Use of Default Cryptographic Key vulnerability in Erlang/OTP ssl (DTLS server) allows predictable DTLS cookie computation during the startup window, enabling source address verification bypass. On DTLS server startup, dtls_server_connection:initial_hello/3 initializes previous_cookie_secret to the empty binary (<<>>) instead of a random value. Because HMAC with an empty key is deterministic, anyone who observes the plaintext ClientHello can compute dtls_handshake:cookie(<<>>, IP, Port, Hello) and forge a valid DTLS cookie before the first rotation of the cookie secret. The DTLS cookie (RFC 6347 §4.2.1) is a denial-of-service mitigation that prevents spoofed source IPs from forcing the server to allocate state and perform expensive cryptographic operations; it is not an authentication mechanism. During the window from server startup until the first secret rotation (0 to 15 seconds), an attacker who can observe the plaintext ClientHello can bypass the source address verification, enabling DTLS handshake amplification with spoofed source addresses. This vulnerability is associated with program file lib/ssl/src/dtls_server_connection.erl and program routine dtls_server_connection:initial_hello/3. This issue affects OTP from OTP 20.0 before OTP 29.0.3, OTP 28.5.0.3 and OTP 27.3.4.14, corresponding to ssl from 8.2 before 11.7.3, 11.6.0.3 and 11.2.12.10.
INFO
Published Date :
July 2, 2026, 5:17 p.m.
Last Modified :
July 24, 2026, 3:18 p.m.
Remotely Exploit :
Yes !
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Affected Products
The following products are affected by CVE-2026-54887
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 4.0 | MEDIUM | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | MEDIUM | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
- Update Erlang/OTP to a version with the fix.
- Ensure random values are used for cookie secrets.
- Apply security updates promptly.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-54887.
| URL | Resource |
|---|---|
| https://cna.erlef.org/cves/CVE-2026-54887.html | Vendor Advisory |
| https://github.com/erlang/otp/commit/888e3bcd72d5406016b9e0de741026bc2a6f114d | Patch |
| https://github.com/erlang/otp/security/advisories/GHSA-p2m2-3c2w-8jp8 | Vendor Advisory |
| https://osv.dev/vulnerability/EEF-CVE-2026-54887 | Third Party Advisory |
| https://www.erlang.org/doc/system/versions.html#order-of-versions | Release Notes |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-54887 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-54887
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-54887 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-54887 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Jul. 24, 2026
Action Type Old Value New Value Changed Description Use of Default Cryptographic Key vulnerability in Erlang/OTP ssl (DTLS server) allows predictable DTLS cookie computation during the startup window, enabling source address verification bypass. On DTLS server startup, dtls_server_connection:initial_hello/3 initializes previous_cookie_secret to the empty binary (<<>>) instead of a random value. Because HMAC with an empty key is deterministic, anyone who observes the plaintext ClientHello can compute dtls_handshake:cookie(<<>>, IP, Port, Hello) and forge a valid DTLS cookie before the first rotation of the cookie secret. The DTLS cookie (RFC 6347 §4.2.1) is a denial-of-service mitigation that prevents spoofed source IPs from forcing the server to allocate state and perform expensive cryptographic operations; it is not an authentication mechanism. During the window from server startup until the first secret rotation (0 to 15 seconds), an attacker who can observe the plaintext ClientHello can bypass the source address verification, enabling DTLS handshake amplification with spoofed source addresses. This vulnerability is associated with program file lib/ssl/src/dtls_server_connection.erl and program routine dtls_server_connection:initial_hello/3. This issue affects OTP from OTP 20.0 before 29.0.3, 28.5.0.3 and 27.3.4.14 corresponding to ssl from 8.2 before 11.7.3, 11.6.0.3 and 11.2.12.10. Use of Default Cryptographic Key vulnerability in Erlang/OTP ssl (DTLS server) allows predictable DTLS cookie computation during the startup window, enabling source address verification bypass. On DTLS server startup, dtls_server_connection:initial_hello/3 initializes previous_cookie_secret to the empty binary (<<>>) instead of a random value. Because HMAC with an empty key is deterministic, anyone who observes the plaintext ClientHello can compute dtls_handshake:cookie(<<>>, IP, Port, Hello) and forge a valid DTLS cookie before the first rotation of the cookie secret. The DTLS cookie (RFC 6347 §4.2.1) is a denial-of-service mitigation that prevents spoofed source IPs from forcing the server to allocate state and perform expensive cryptographic operations; it is not an authentication mechanism. During the window from server startup until the first secret rotation (0 to 15 seconds), an attacker who can observe the plaintext ClientHello can bypass the source address verification, enabling DTLS handshake amplification with spoofed source addresses. This vulnerability is associated with program file lib/ssl/src/dtls_server_connection.erl and program routine dtls_server_connection:initial_hello/3. This issue affects OTP from OTP 20.0 before OTP 29.0.3, OTP 28.5.0.3 and OTP 27.3.4.14, corresponding to ssl from 8.2 before 11.7.3, 11.6.0.3 and 11.2.12.10. -
Initial Analysis by [email protected]
Jul. 07, 2026
Action Type Old Value New Value Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N Added CPE Configuration OR *cpe:2.3:a:erlang:erlang/otp:*:*:*:*:*:*:*:* versions from (including) 28.0 up to (excluding) 28.5.0.3 *cpe:2.3:a:erlang:erlang/otp:*:*:*:*:*:*:*:* versions from (including) 29.0 up to (excluding) 29.0.3 *cpe:2.3:a:erlang:erlang/ssl:*:*:*:*:*:*:*:* versions from (including) 11.3 up to (excluding) 11.6.0.3 *cpe:2.3:a:erlang:erlang/ssl:*:*:*:*:*:*:*:* versions from (including) 11.7 up to (excluding) 11.7.3 *cpe:2.3:a:erlang:erlang/otp:*:*:*:*:*:*:*:* versions from (including) 20.0 up to (excluding) 27.3.4.14 *cpe:2.3:a:erlang:erlang/ssl:*:*:*:*:*:*:*:* versions from (including) 8.2 up to (excluding) 11.2.12.10 Added Reference Type EEF: https://cna.erlef.org/cves/CVE-2026-54887.html Types: Vendor Advisory Added Reference Type EEF: https://github.com/erlang/otp/commit/888e3bcd72d5406016b9e0de741026bc2a6f114d Types: Patch Added Reference Type EEF: https://github.com/erlang/otp/security/advisories/GHSA-p2m2-3c2w-8jp8 Types: Vendor Advisory Added Reference Type EEF: https://osv.dev/vulnerability/EEF-CVE-2026-54887 Types: Third Party Advisory Added Reference Type EEF: https://www.erlang.org/doc/system/versions.html#order-of-versions Types: Release Notes -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 02, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-54887', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-02T17:28:36.936306Z'} -
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Jul. 02, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/erlang/otp', 'vendor': 'Erlang', 'modules': ['dtls_server_connection'], 'product': 'OTP', 'versions': [{'status': 'affected', 'changes': [{'at': '11.7.3', 'status': 'unaffected'}, {'at': '11.6.0.3', 'status': 'unaffected'}, {'at': '11.2.12.10', 'status': 'unaffected'}], 'version': '8.2', 'lessThan': '*', 'versionType': 'otp'}], 'packageURL': 'pkg:otp/ssl?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git', 'packageName': 'ssl', 'programFiles': ['src/dtls_server_connection.erl'], 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'dtls_server_connection:initial_hello/3'}]}, {'cpes': ['cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/erlang/otp', 'vendor': 'Erlang', 'modules': ['dtls_server_connection'], 'product': 'OTP', 'versions': [{'status': 'affected', 'changes': [{'at': '29.0.3', 'status': 'unaffected'}, {'at': '28.5.0.3', 'status': 'unaffected'}, {'at': '27.3.4.14', 'status': 'unaffected'}], 'version': '20.0', 'lessThan': '*', 'versionType': 'otp'}, {'status': 'affected', 'version': 'e594aad2f87aab39e99fccf9e021bc94e0bbf7d4', 'lessThan': '888e3bcd72d5406016b9e0de741026bc2a6f114d', 'versionType': 'git'}], 'packageURL': 'pkg:github/erlang/otp', 'packageName': 'erlang/otp', 'programFiles': ['lib/ssl/src/dtls_server_connection.erl'], 'collectionURL': 'https://github.com', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': 'dtls_server_connection:initial_hello/3'}]}] Added Description Use of Default Cryptographic Key vulnerability in Erlang/OTP ssl (DTLS server) allows predictable DTLS cookie computation during the startup window, enabling source address verification bypass. On DTLS server startup, dtls_server_connection:initial_hello/3 initializes previous_cookie_secret to the empty binary (<<>>) instead of a random value. Because HMAC with an empty key is deterministic, anyone who observes the plaintext ClientHello can compute dtls_handshake:cookie(<<>>, IP, Port, Hello) and forge a valid DTLS cookie before the first rotation of the cookie secret. The DTLS cookie (RFC 6347 §4.2.1) is a denial-of-service mitigation that prevents spoofed source IPs from forcing the server to allocate state and perform expensive cryptographic operations; it is not an authentication mechanism. During the window from server startup until the first secret rotation (0 to 15 seconds), an attacker who can observe the plaintext ClientHello can bypass the source address verification, enabling DTLS handshake amplification with spoofed source addresses. This vulnerability is associated with program file lib/ssl/src/dtls_server_connection.erl and program routine dtls_server_connection:initial_hello/3. This issue affects OTP from OTP 20.0 before 29.0.3, 28.5.0.3 and 27.3.4.14 corresponding to ssl from 8.2 before 11.7.3, 11.6.0.3 and 11.2.12.10. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/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 Added CWE CWE-1394 Added Reference https://cna.erlef.org/cves/CVE-2026-54887.html Added Reference https://github.com/erlang/otp/commit/888e3bcd72d5406016b9e0de741026bc2a6f114d Added Reference https://github.com/erlang/otp/security/advisories/GHSA-p2m2-3c2w-8jp8 Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-54887 Added Reference https://www.erlang.org/doc/system/versions.html#order-of-versions