How severe is CVE-2021-39515?

CVE-2021-39515 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2021-39515 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-39515?

CVE-2021-39515 affects Jpeg Libjpeg. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-39515?

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

When was CVE-2021-39515 published?

CVE-2021-39515 was published on 2021-09-20 and last updated on 2026-06-17.

CVE-2021-39515

CVE-2021-39515 is a medium-severity vulnerability in Jpeg Libjpeg with a CVSS 3.x base score of 6.5. 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-476.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 4.3
EPSS exploit prediction: 1% (53rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-476
Affected product: Jpeg Libjpeg
Published: 2021-09-20
Last modified: 2026-06-17

Description

An issue was discovered in libjpeg through 2020021. A NULL pointer dereference exists in the function SampleInterleavedLSScan::ParseMCU() located in sampleinterleavedlsscan.cpp. It allows an attacker to cause Denial of Service.

Frequently asked questions

What is CVE-2021-39515?: An issue was discovered in libjpeg through 2020021. A NULL pointer dereference exists in the function SampleInterleavedLSScan::ParseMCU() located in sampleinterleavedlsscan.cpp. It allows an attacker to cause Denial of Service.
How severe is CVE-2021-39515?: CVE-2021-39515 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2021-39515 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-39515?: CVE-2021-39515 affects Jpeg Libjpeg. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-39515?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-39515 published?: CVE-2021-39515 was published on 2021-09-20 and last updated on 2026-06-17.

References

https://github.com/thorfdbg/libjpeg/issues/37

Affected products (1)

cpe:2.3:a:jpeg:libjpeg:*:*:*:*:*:*:*:*

More vulnerabilities in Jpeg Libjpeg

CVE-2022-37768 — High (CVSS 7.5): libjpeg commit 281daa9 was discovered to contain an infinite loop via the component Frame::ParseTrailer.
CVE-2023-37837 — Medium (CVSS 6.5): libjpeg commit db33a6e was discovered to contain a heap buffer overflow via LineBitmapRequester::EncodeRegion at…
CVE-2023-37836 — Medium (CVSS 6.5): libjpeg commit db33a6e was discovered to contain a reachable assertion via BitMapHook::BitMapHook at bitmaphook.cpp.…
CVE-2022-37770 — Medium (CVSS 6.5): libjpeg commit 281daa9 was discovered to contain a segmentation fault via LineMerger::GetNextLowpassLine at…
CVE-2022-37769 — Medium (CVSS 6.5): libjpeg commit 281daa9 was discovered to contain a segmentation fault via HuffmanDecoder::Get at huffmandecoder.hpp.…
CVE-2022-32978 — Medium (CVSS 6.5): There is an assertion failure in SingleComponentLSScan::ParseMCU in singlecomponentlsscan.cpp in libjpeg before 1.64…

All CVEs affecting Jpeg Libjpeg →

Other CWE-476 (NULL Pointer Dereference) vulnerabilities

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