How severe is CVE-2026-35189?

CVE-2026-35189 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2026-35189 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-35189?

CVE-2026-35189 affects Openssl. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-35189?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2026-35189 published?

CVE-2026-35189 was published on 2026-09-29 and last updated on 2026-10-08.

CVE-2026-35189

CVE-2026-35189 is a medium-severity vulnerability in Openssl with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
EPSS exploit prediction: 0% (18th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-770
Affected product: Openssl
Published: 2026-09-29
Last modified: 2026-10-08

Description

Issue summary: A certificate with many nameRelativeToCRLIssuer CRL distribution points causes disproportionate heap growth when OpenSSL caches X.509 extensions. Impact summary: Receiving a crafted certificate from a malicious peer can lead to significant memory pressure and possible Denial of Service in clients or in servers that solicit client certificates. CWE: CWE-770: Allocation of Resources Without Limits or Throttling Description: A certificate or a set of certificates that fits under the limit for size of certificates accepted from the peer (~100 KiB) can result in allocation of several hundred MiB of resident memory on the receiving side during a normal TLS handshake. This may be enough to crash the client or server, if multiple concurrent connections lead to similarly large memory allocations. The fix postpones processing of the CRL distribution points extensions in certificates to the time when the processed value is required for CRL processing. This avoids keeping large memory allocations for a long time when such certificates are received. FIPS impact: no The affected code is outside the FIPS module boundary.

Frequently asked questions

What is CVE-2026-35189?: Issue summary: A certificate with many nameRelativeToCRLIssuer CRL distribution points causes disproportionate heap growth when OpenSSL caches X.509 extensions. Impact summary: Receiving a crafted certificate from a malicious peer can lead to significant memory pressure and possible Denial of Service in clients or in servers that solicit client certificates. CWE: CWE-770: Allocation of Resources Without Limits or Throttling Description: A certificate or a set of certificates that fits under the limit for size of certificates accepted from the peer (~100 KiB) can result in allocation of several hundred MiB of resident memory on the receiving side during a normal TLS handshake. This may be enough to crash the client or server, if multiple concurrent connections lead to similarly large memory allocations. The fix postpones processing of the CRL distribution points extensions in certificates to the time when the processed value is required for CRL processing. This avoids keeping large memory allocations for a long time when such certificates are received. FIPS impact: no The affected code is outside the FIPS module boundary.
How severe is CVE-2026-35189?: CVE-2026-35189 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2026-35189 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (18th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-35189?: CVE-2026-35189 affects Openssl. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-35189?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-35189 published?: CVE-2026-35189 was published on 2026-09-29 and last updated on 2026-10-08.

References

Affected products (1)

cpe:2.3:a:openssl:openssl:*:*:*:*:*:*:*:*

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Other CWE-770 (Allocation of Resources Without Limits or Throttling) vulnerabilities

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CVE-2026-74878 — Critical (CVSS 9.8): openssl_encrypt versions before 1.4.0 use an in-memory rate limiter for TOTP brute-force protection that is not shared…
CVE-2026-31283 — Critical (CVSS 9.8): In Totara LMS v19.1.5 and before, the forgot password API does not implement rate limiting for the target email…

Browse all CWE-770 (Allocation of Resources Without Limits or Throttling) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

159.223.95.100 (ipv4-addr)
194.50.173.43 (ipv4-addr)
181.224.200.6 (ipv4-addr)
144.202.0.81 (ipv4-addr)
78.189.135.34 (ipv4-addr)
42.192.101.199 (ipv4-addr)
93.58.255.46 (ipv4-addr)
41.223.107.27 (ipv4-addr)