How severe is CVE-2021-29258?

CVE-2021-29258 has a CVSS 3.x base score of 7.5, rated high 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 high.

Is CVE-2021-29258 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-29258?

CVE-2021-29258 primarily affects Envoyproxy Envoy. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-29258?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2021-29258 published?

CVE-2021-29258 was published on 2021-05-20 and last updated on 2026-06-17.

CVE-2021-29258

CVE-2021-29258 is a high-severity vulnerability in Envoyproxy Envoy with a CVSS 3.x base score of 7.5. 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-617.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 5.0
EPSS exploit prediction: 2% (75th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-617
Affected product: Envoyproxy Envoy
Published: 2021-05-20
Last modified: 2026-06-17

Description

An issue was discovered in Envoy 1.14.0. There is a remotely exploitable crash for HTTP2 Metadata, because an empty METADATA map triggers a Reachable Assertion.

Frequently asked questions

What is CVE-2021-29258?: An issue was discovered in Envoy 1.14.0. There is a remotely exploitable crash for HTTP2 Metadata, because an empty METADATA map triggers a Reachable Assertion.
How severe is CVE-2021-29258?: CVE-2021-29258 has a CVSS 3.x base score of 7.5, rated high 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 high.
Is CVE-2021-29258 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (75th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-29258?: CVE-2021-29258 primarily affects Envoyproxy Envoy. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-29258?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2021-29258 published?: CVE-2021-29258 was published on 2021-05-20 and last updated on 2026-06-17.

References

Affected products (4)

cpe:2.3:a:envoyproxy:envoy:1.14.6:*:*:*:*:*:*:*
cpe:2.3:a:envoyproxy:envoy:1.15.3:*:*:*:*:*:*:*
cpe:2.3:a:envoyproxy:envoy:1.16.2:*:*:*:*:*:*:*
cpe:2.3:a:envoyproxy:envoy:1.17.1:*:*:*:*:*:*:*

More vulnerabilities in Envoyproxy Envoy

CVE-2022-29226 — Critical (CVSS 10.0): Envoy is a cloud-native high-performance proxy. In versions prior to 1.22.1 the OAuth filter implementation does not…
CVE-2019-18802 — Critical (CVSS 9.8): An issue was discovered in Envoy 1.12.0. An untrusted remote client may send an HTTP header (such as Host) with…
CVE-2019-18801 — Critical (CVSS 9.8): An issue was discovered in Envoy 1.12.0. An untrusted remote client may send HTTP/2 requests that write to the heap…
CVE-2020-35470 — High (CVSS 8.8): Envoy before 1.16.1 logs an incorrect downstream address because it considers only the directly connected peer, not the…
CVE-2024-23324 — High (CVSS 8.6): Envoy is a high-performance edge/middle/service proxy. External authentication can be bypassed by downstream…
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Other CWE-617 (Reachable Assertion) vulnerabilities

CVE-2020-3615 — Critical (CVSS 9.8): Valid deauth/disassoc frames is dropped in case if RMF is enabled and some rouge peer keep on sending rogue…
CVE-2019-9795 — Critical (CVSS 9.8): A vulnerability where type-confusion in the IonMonkey just-in-time (JIT) compiler could potentially be used by…
CVE-2026-31739 — High (CVSS 8.8): In the Linux kernel, the following vulnerability has been resolved: crypto: tegra - Add missing CRYPTO_ALG_ASYNC The…
CVE-2020-12417 — High (CVSS 8.8): Due to confusion about ValueTags on JavaScript Objects, an object may pass through the type barrier, resulting in…
CVE-2020-6623 — High (CVSS 8.8): stb stb_truetype.h through 1.22 has an assertion failure in stbtt__cff_get_index.
CVE-2020-6619 — High (CVSS 8.8): stb stb_truetype.h through 1.22 has an assertion failure in stbtt__buf_seek.

Browse all CWE-617 (Reachable Assertion) vulnerabilities →