Issue summary: Receiving a DTLS record for a future epoch while a handshake
\nis in progress causes OpenSSL to buffer far more memory than the record
\nitself requires.<\/p>\n
Impact summary: A peer can use a small amount of network traffic to make an
\nOpenSSL DTLS endpoint retain a disproportionately large amount of memory,
\nwhich may lead to a Denial of Service.<\/p>\n
CWE: CWE-405: Asymmetric Resource Consumption (Amplification)<\/p>\n
Description: While a DTLS handshake is in progress, a peer may legitimately
\nhave already moved on to the next epoch (for example, having sent its
\nChangeCipherSpec and Finished messages) before the local endpoint has
\nprocessed the same transition, typically because of reordering on the
\nunderlying UDP transport. OpenSSL buffers such early records so that they
\ncan be processed once the local endpoint catches up.<\/p>\n
Buffering a record currently retains the entire read buffer it arrived in,
\nwhich is sized to hold the largest possible DTLS record (around 16
\nkilobytes), rather than just the bytes that make up the record itself. Up
\nto 100 such records may be buffered per connection. As a result, a peer
\nthat sends a stream of small forged records claiming to belong to the next
\nepoch can cause an OpenSSL DTLS endpoint to retain around 1.7 megabytes of
\nmemory, despite sending only a small fraction of that amount of data over
\nthe network.<\/p>\n
An attacker therefore gains a memory amplification factor of around 1200,
\nand can multiply the effect across as many associations as it is able to
\nopen, making this a remote memory exhaustion Denial of Service risk for
\nDTLS servers. Since the memory retained per connection remains bounded,
\nand any limit an application already places on the number of concurrent
\nassociations also bounds the total exposure, this issue has been assessed
\nas Low severity.<\/p>\n
FIPS impact: no<\/p>\n
No FIPS modules are affected by this issue as the affected code is outside
\nthe OpenSSL FIPS module boundary.<\/p>\n
OpenSSL 4.0, 3.6, 3.5, 3.4, 3.0, 1.1.1 and 1.0.2 are vulnerable to this
\nissue.<\/p>\n
OpenSSL 4.0 users should upgrade to OpenSSL 4.0.2.
\nOpenSSL 3.6 users should upgrade to OpenSSL 3.6.4.
\nOpenSSL 3.5 users should upgrade to OpenSSL 3.5.8.
\nOpenSSL 3.4 users should upgrade to OpenSSL 3.4.7.
\nOpenSSL 3.0 users should upgrade to OpenSSL 3.0.22.<\/p>\n
Premium support customers only:
\nOpenSSL 1.1.1 users should upgrade to OpenSSL 1.1.1zi
\nOpenSSL 1.0.2 users should upgrade to OpenSSL 1.0.2zr<\/p>\n
This issue was reported on 18 May 2026 by Amazon Web Services.
\nThe fix has been developed by Matt Caswell.<\/p>\n
— cut (non-publishing metadata for internal use) —
\nReported by: Amazon Web Services
\nFixed by: Matt Caswell<\/p>\n","protected":false},"excerpt":{"rendered":"
Issue summary: Receiving a DTLS record for a future epoch while a handshake
\nis in progress causes OpenSSL to buffer far more memory than the record
\nitself requires.<\/p>\n
Impact summary: A peer can use a s<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-11558","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/11558","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=11558"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=11558"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=11558"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}