CVE-2026-72897— Out-of-Bounds Access After SSL_set_SSL_CTX() During a Handshake
一分钟漏洞结论
影响对象
OpenSSL OpenSSL
利用判断
尚无明确在野利用证据，仍需结合暴露面评估
建议动作
优先检查厂商安全公告和参考链接中的修复版本；无法立即升级时，限制受影响服务暴露并加强监测。
Issue summary: A TLS server that calls SSL_set_SSL_CTX() to switch a connection to a different SSL_CTX part way through a handshake may access memory beyond the end of an internal array if the replacement context knows about more provider signature algorithms
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一、 漏洞 CVE-2026-72897 基础信息
漏洞信息
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Vulnerability Title
Out-of-Bounds Access After SSL_set_SSL_CTX() During a Handshake
来源: CVE Program / CVE List V5
Vulnerability Description
Issue summary: A TLS server that calls SSL_set_SSL_CTX() to switch a
connection to a different SSL_CTX part way through a handshake may access
memory beyond the end of an internal array if the replacement context knows
about more provider signature algorithms than the context the connection was
created from. Applications which never call SSL_set_SSL_CTX() are not
affected.
Impact summary: A remote peer may be able to cause a small out-of-bounds
read, and in some circumstances a fixed-value out-of-bounds write, on the
server heap. This may lead to a Denial of Service.
CWE: CWE-787: Out-of-bounds Write
Description: A TLS connection records how many certificate slots it has
when it is created, taken from the SSL_CTX that created it: the built-in
certificate types plus one slot for each provider TLS-SIGALG entry that
context was aware of. That count sizes an internal array of per-slot
certificate validity flags.
An application may replace a connection's SSL_CTX part way through the
handshake by calling SSL_set_SSL_CTX(), most commonly from a servername
callback in order to serve a different virtual host. Doing so did not
refresh the recorded count. A provider signature algorithm's slot index is
its position in the list of whichever context resolves it, so if the
replacement context is aware of more of them than the original, an
algorithm offered by the peer can resolve to an index beyond the end of the
array. Processing the peer's signature algorithms then reads one four byte
word past the end for each such algorithm and, where the word read is zero,
writes a fixed value over it. A peer offering many of them can corrupt heap
metadata and abort the process.
Only provider signature algorithms which occupy one of the excess slots,
and which the server also has configured, have this effect. Codepoints the
replacement context does not recognise are discarded without being resolved
to a slot, and provider signature algorithms are usable only from TLS 1.3.
The two contexts must therefore be aware of different numbers of provider
signature algorithms, which requires separate library contexts, a provider
loaded between the two being created, or providers which differ in what
they advertise - in 4.0, for example, the default provider advertises SM2
where the FIPS provider does not. A deployment meeting the condition is
also unable to negotiate the affected algorithms with legitimate clients,
since the same stale count hides the corresponding certificates, so the
misconfiguration is likely to be noticed. For that reason, and because the
configuration is not the default, this issue has been assessed as Low
severity.
FIPS impact: no
No FIPS modules are affected by this issue as the affected code is outside
the OpenSSL FIPS module boundary.
来源: CVE Program / CVE List V5
CVSS Information
N/A
来源: CVE Program / CVE List V5
Vulnerability Type
跨界内存写
来源: CVE Program / CVE List V5
受影响产品
二、漏洞 CVE-2026-72897 的公开POC
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CVE-2026-72897 其他参考 (5)
-
https://openssl-library.org/news/secadv/20260929.txt vendor-advisory
同批安全公告 · OpenSSL · 2026-09-29 · 共 14 条
| CVE-2026-35189 | Excessive Memory Allocation in Relative CRLDP Processing | |
| CVE-2026-35191 | QUIC Unvalidated Amplification Credit may be Over Accounted | |
| CVE-2026-75806 | Unauthenticated and Undersized DTLS 1.2 AEAD Record Causes DoS | |
| CVE-2026-75804 | QUIC Connection-Level Flow Control is Not Enforced for Streams | |
| CVE-2026-75805 | NULL Pointer Dereference in CMP Client Revocation Response Handling | |
| CVE-2026-42772 | Potential CPU DoS via O(n^2) Fragment Reassembly in QUIC | |
| CVE-2026-54873 | QUIC STREAM Fragment Metadata DoS | |
| CVE-2026-54872 | Timing Side-Channel in Scalar Multiplication for Non-NIST EC Curves | |
| CVE-2026-54875 | Non-Constant-Time SM2 Scalar Multiplication on ARM64 and RISC-V | |
| CVE-2026-77696 | Timing Side-Channel in SM2 Signature Generation | |
| CVE-2026-84782 | DTLS Retransmits Handshake Messages From a Stale Buffer Offset | |
| CVE-2026-84784 | QUIC: Unbounded RETIRE_CONNECTION_ID Backlog | |
| CVE-2026-84783 | Use-After-Free in X.509 Extension Cache Under Concurrent Use |
IV. Related Vulnerabilities
Same product: OpenSSL
-
CVE-2026-84784
QUIC: Unbounded RETIRE_CONNECTION_ID Backlog -
CVE-2026-84783
Use-After-Free in X.509 Extension Cache Under Concurrent Use -
CVE-2026-84782
DTLS Retransmits Handshake Messages From a Stale Buffer Offs -
CVE-2026-77696
Timing Side-Channel in SM2 Signature Generation -
CVE-2026-75806
Unauthenticated and Undersized DTLS 1.2 AEAD Record Causes D
Same vendor: OpenSSL
-
CVE-2026-84784
QUIC: Unbounded RETIRE_CONNECTION_ID Backlog -
CVE-2026-84783
Use-After-Free in X.509 Extension Cache Under Concurrent Use -
CVE-2026-84782
DTLS Retransmits Handshake Messages From a Stale Buffer Offs -
CVE-2026-77696
Timing Side-Channel in SM2 Signature Generation -
CVE-2026-75806
Unauthenticated and Undersized DTLS 1.2 AEAD Record Causes D
Same weakness: CWE-787
V. Comments for CVE-2026-72897
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